Why homologous sides are sides opposite to homologous angles?

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In Plane and solid geometry by Fletcher Durell, he mentions in page 34 that




91. Homologous angles of two mutually equiangular triangles are corresponding angles in those triangles.



Homologous sides of two mutually equiangular triangles are sides
opposite homologous angles in those triangles.




I hope to see that, length of an opposite side of the given angle doesn't have to be influenced by it's opposite angle. So why does the author say that "homologous sides are sides opposite to homologous angles"?



I'm asking this question because in some proofs like in Proposition XVI : it says triangle $F'BH$ = triangle $BHC$, so $F'H$ = $CH$ (homologous sides of equal triangles). What is the author trying to say by this statement?







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    In Plane and solid geometry by Fletcher Durell, he mentions in page 34 that




    91. Homologous angles of two mutually equiangular triangles are corresponding angles in those triangles.



    Homologous sides of two mutually equiangular triangles are sides
    opposite homologous angles in those triangles.




    I hope to see that, length of an opposite side of the given angle doesn't have to be influenced by it's opposite angle. So why does the author say that "homologous sides are sides opposite to homologous angles"?



    I'm asking this question because in some proofs like in Proposition XVI : it says triangle $F'BH$ = triangle $BHC$, so $F'H$ = $CH$ (homologous sides of equal triangles). What is the author trying to say by this statement?







    share|cite|improve this question





















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      favorite









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      In Plane and solid geometry by Fletcher Durell, he mentions in page 34 that




      91. Homologous angles of two mutually equiangular triangles are corresponding angles in those triangles.



      Homologous sides of two mutually equiangular triangles are sides
      opposite homologous angles in those triangles.




      I hope to see that, length of an opposite side of the given angle doesn't have to be influenced by it's opposite angle. So why does the author say that "homologous sides are sides opposite to homologous angles"?



      I'm asking this question because in some proofs like in Proposition XVI : it says triangle $F'BH$ = triangle $BHC$, so $F'H$ = $CH$ (homologous sides of equal triangles). What is the author trying to say by this statement?







      share|cite|improve this question











      In Plane and solid geometry by Fletcher Durell, he mentions in page 34 that




      91. Homologous angles of two mutually equiangular triangles are corresponding angles in those triangles.



      Homologous sides of two mutually equiangular triangles are sides
      opposite homologous angles in those triangles.




      I hope to see that, length of an opposite side of the given angle doesn't have to be influenced by it's opposite angle. So why does the author say that "homologous sides are sides opposite to homologous angles"?



      I'm asking this question because in some proofs like in Proposition XVI : it says triangle $F'BH$ = triangle $BHC$, so $F'H$ = $CH$ (homologous sides of equal triangles). What is the author trying to say by this statement?









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      share|cite|improve this question




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      asked Jul 16 at 22:03









      justin

      217113




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          It is a definition, a name to refer to these sides. It does not imply that their length are pairwise equal in general (although the ratio of the lengths is the same for all three pairs).



          In the example, it is important to note that it is not "homologous sides of mutually equiangular triangles" but "homologous sides of equal triangles". Equal triangles, in this context, seems to mean isometric.






          share|cite|improve this answer





















          • Can the term 'corresponding' be used in lieu of 'homologous' or whether 'homologous' has some special meaning other than 'corresponding'?
            – justin
            Jul 17 at 21:19










          • @justin Of course you could use that instead, it would also make sense. But the authors of the book want to make everything clear and state which term they are going to use, once and for all.
            – Arnaud Mortier
            Jul 17 at 21:26











          • Is there any specific reason, in choosing the side opposite of the homologous angle to be the homologous side of an equianglular triangle?
            – justin
            Jul 17 at 21:32










          • @justin If you look at two such triangles, it' clear: homologous sides are those that you would naturally put into pairs if you had to form a correspondence between the sides of the two triangles. The ratio of the lengths is the same for all pairs.
            – Arnaud Mortier
            Jul 17 at 21:38










          • Does this mean that for equiangluar triangles, the ratio of the corresponding sides would always be in a proportion?
            – justin
            Jul 17 at 21:41










          Your Answer




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          up vote
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          down vote













          It is a definition, a name to refer to these sides. It does not imply that their length are pairwise equal in general (although the ratio of the lengths is the same for all three pairs).



          In the example, it is important to note that it is not "homologous sides of mutually equiangular triangles" but "homologous sides of equal triangles". Equal triangles, in this context, seems to mean isometric.






          share|cite|improve this answer





















          • Can the term 'corresponding' be used in lieu of 'homologous' or whether 'homologous' has some special meaning other than 'corresponding'?
            – justin
            Jul 17 at 21:19










          • @justin Of course you could use that instead, it would also make sense. But the authors of the book want to make everything clear and state which term they are going to use, once and for all.
            – Arnaud Mortier
            Jul 17 at 21:26











          • Is there any specific reason, in choosing the side opposite of the homologous angle to be the homologous side of an equianglular triangle?
            – justin
            Jul 17 at 21:32










          • @justin If you look at two such triangles, it' clear: homologous sides are those that you would naturally put into pairs if you had to form a correspondence between the sides of the two triangles. The ratio of the lengths is the same for all pairs.
            – Arnaud Mortier
            Jul 17 at 21:38










          • Does this mean that for equiangluar triangles, the ratio of the corresponding sides would always be in a proportion?
            – justin
            Jul 17 at 21:41














          up vote
          0
          down vote













          It is a definition, a name to refer to these sides. It does not imply that their length are pairwise equal in general (although the ratio of the lengths is the same for all three pairs).



          In the example, it is important to note that it is not "homologous sides of mutually equiangular triangles" but "homologous sides of equal triangles". Equal triangles, in this context, seems to mean isometric.






          share|cite|improve this answer





















          • Can the term 'corresponding' be used in lieu of 'homologous' or whether 'homologous' has some special meaning other than 'corresponding'?
            – justin
            Jul 17 at 21:19










          • @justin Of course you could use that instead, it would also make sense. But the authors of the book want to make everything clear and state which term they are going to use, once and for all.
            – Arnaud Mortier
            Jul 17 at 21:26











          • Is there any specific reason, in choosing the side opposite of the homologous angle to be the homologous side of an equianglular triangle?
            – justin
            Jul 17 at 21:32










          • @justin If you look at two such triangles, it' clear: homologous sides are those that you would naturally put into pairs if you had to form a correspondence between the sides of the two triangles. The ratio of the lengths is the same for all pairs.
            – Arnaud Mortier
            Jul 17 at 21:38










          • Does this mean that for equiangluar triangles, the ratio of the corresponding sides would always be in a proportion?
            – justin
            Jul 17 at 21:41












          up vote
          0
          down vote










          up vote
          0
          down vote









          It is a definition, a name to refer to these sides. It does not imply that their length are pairwise equal in general (although the ratio of the lengths is the same for all three pairs).



          In the example, it is important to note that it is not "homologous sides of mutually equiangular triangles" but "homologous sides of equal triangles". Equal triangles, in this context, seems to mean isometric.






          share|cite|improve this answer













          It is a definition, a name to refer to these sides. It does not imply that their length are pairwise equal in general (although the ratio of the lengths is the same for all three pairs).



          In the example, it is important to note that it is not "homologous sides of mutually equiangular triangles" but "homologous sides of equal triangles". Equal triangles, in this context, seems to mean isometric.







          share|cite|improve this answer













          share|cite|improve this answer



          share|cite|improve this answer











          answered Jul 16 at 22:26









          Arnaud Mortier

          19.2k22159




          19.2k22159











          • Can the term 'corresponding' be used in lieu of 'homologous' or whether 'homologous' has some special meaning other than 'corresponding'?
            – justin
            Jul 17 at 21:19










          • @justin Of course you could use that instead, it would also make sense. But the authors of the book want to make everything clear and state which term they are going to use, once and for all.
            – Arnaud Mortier
            Jul 17 at 21:26











          • Is there any specific reason, in choosing the side opposite of the homologous angle to be the homologous side of an equianglular triangle?
            – justin
            Jul 17 at 21:32










          • @justin If you look at two such triangles, it' clear: homologous sides are those that you would naturally put into pairs if you had to form a correspondence between the sides of the two triangles. The ratio of the lengths is the same for all pairs.
            – Arnaud Mortier
            Jul 17 at 21:38










          • Does this mean that for equiangluar triangles, the ratio of the corresponding sides would always be in a proportion?
            – justin
            Jul 17 at 21:41
















          • Can the term 'corresponding' be used in lieu of 'homologous' or whether 'homologous' has some special meaning other than 'corresponding'?
            – justin
            Jul 17 at 21:19










          • @justin Of course you could use that instead, it would also make sense. But the authors of the book want to make everything clear and state which term they are going to use, once and for all.
            – Arnaud Mortier
            Jul 17 at 21:26











          • Is there any specific reason, in choosing the side opposite of the homologous angle to be the homologous side of an equianglular triangle?
            – justin
            Jul 17 at 21:32










          • @justin If you look at two such triangles, it' clear: homologous sides are those that you would naturally put into pairs if you had to form a correspondence between the sides of the two triangles. The ratio of the lengths is the same for all pairs.
            – Arnaud Mortier
            Jul 17 at 21:38










          • Does this mean that for equiangluar triangles, the ratio of the corresponding sides would always be in a proportion?
            – justin
            Jul 17 at 21:41















          Can the term 'corresponding' be used in lieu of 'homologous' or whether 'homologous' has some special meaning other than 'corresponding'?
          – justin
          Jul 17 at 21:19




          Can the term 'corresponding' be used in lieu of 'homologous' or whether 'homologous' has some special meaning other than 'corresponding'?
          – justin
          Jul 17 at 21:19












          @justin Of course you could use that instead, it would also make sense. But the authors of the book want to make everything clear and state which term they are going to use, once and for all.
          – Arnaud Mortier
          Jul 17 at 21:26





          @justin Of course you could use that instead, it would also make sense. But the authors of the book want to make everything clear and state which term they are going to use, once and for all.
          – Arnaud Mortier
          Jul 17 at 21:26













          Is there any specific reason, in choosing the side opposite of the homologous angle to be the homologous side of an equianglular triangle?
          – justin
          Jul 17 at 21:32




          Is there any specific reason, in choosing the side opposite of the homologous angle to be the homologous side of an equianglular triangle?
          – justin
          Jul 17 at 21:32












          @justin If you look at two such triangles, it' clear: homologous sides are those that you would naturally put into pairs if you had to form a correspondence between the sides of the two triangles. The ratio of the lengths is the same for all pairs.
          – Arnaud Mortier
          Jul 17 at 21:38




          @justin If you look at two such triangles, it' clear: homologous sides are those that you would naturally put into pairs if you had to form a correspondence between the sides of the two triangles. The ratio of the lengths is the same for all pairs.
          – Arnaud Mortier
          Jul 17 at 21:38












          Does this mean that for equiangluar triangles, the ratio of the corresponding sides would always be in a proportion?
          – justin
          Jul 17 at 21:41




          Does this mean that for equiangluar triangles, the ratio of the corresponding sides would always be in a proportion?
          – justin
          Jul 17 at 21:41












           

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