Angle between hour and minute hand at 2:42

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up vote
1
down vote

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Angle made by hour hand: 



 for 2 hours: 2*30 = 60

 for 42 mins: (42/60) * 30 = 21

 Total angle made by hour hand is: (60 + 21)= 81 degrees


Angle made by minute hand:



 for 42 min: 42*6 = 252 

 Total angle made by minute hand is: 252 degrees


The angle between the minute and hour hand is: (252-81) = 171 degrees



My question is about "why is 171 degrees a wrong answer" and the correct answer is 189 degrees




trigonometry




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  • 1




    I would not expect either. On most clocks, by 2:42 the hour hand would be considerably beyond 2; it would be closer to 3.
    – badjohn
    Jul 28 at 11:41






  • 1




    $171^circ$ is the correct answer, unless a clearly defined oriented angle is meant, e.g., "counterclockwise from the hour hand to the minute hand".
    – Christian Blatter
    Jul 28 at 13:53










  • @ChristianBlatter, I think orientation is defined as counterclockwise. And we should measure angles in the positive direction
    – dEmigOd
    Jul 28 at 14:53














up vote
1
down vote

favorite












Angle made by hour hand: 



 for 2 hours: 2*30 = 60

 for 42 mins: (42/60) * 30 = 21

 Total angle made by hour hand is: (60 + 21)= 81 degrees


Angle made by minute hand:



 for 42 min: 42*6 = 252 

 Total angle made by minute hand is: 252 degrees


The angle between the minute and hour hand is: (252-81) = 171 degrees



My question is about "why is 171 degrees a wrong answer" and the correct answer is 189 degrees




trigonometry




share|cite|improve this question

















  • 1




    I would not expect either. On most clocks, by 2:42 the hour hand would be considerably beyond 2; it would be closer to 3.
    – badjohn
    Jul 28 at 11:41






  • 1




    $171^circ$ is the correct answer, unless a clearly defined oriented angle is meant, e.g., "counterclockwise from the hour hand to the minute hand".
    – Christian Blatter
    Jul 28 at 13:53










  • @ChristianBlatter, I think orientation is defined as counterclockwise. And we should measure angles in the positive direction
    – dEmigOd
    Jul 28 at 14:53












up vote
1
down vote

favorite









up vote
1
down vote

favorite











Angle made by hour hand: 



 for 2 hours: 2*30 = 60

 for 42 mins: (42/60) * 30 = 21

 Total angle made by hour hand is: (60 + 21)= 81 degrees


Angle made by minute hand:



 for 42 min: 42*6 = 252 

 Total angle made by minute hand is: 252 degrees


The angle between the minute and hour hand is: (252-81) = 171 degrees



My question is about "why is 171 degrees a wrong answer" and the correct answer is 189 degrees




trigonometry




share|cite|improve this question













Angle made by hour hand: 



 for 2 hours: 2*30 = 60

 for 42 mins: (42/60) * 30 = 21

 Total angle made by hour hand is: (60 + 21)= 81 degrees


Angle made by minute hand:



 for 42 min: 42*6 = 252 

 Total angle made by minute hand is: 252 degrees


The angle between the minute and hour hand is: (252-81) = 171 degrees



My question is about "why is 171 degrees a wrong answer" and the correct answer is 189 degrees





trigonometry





share|cite|improve this question












share|cite|improve this question




share|cite|improve this question








edited Jul 28 at 11:35









Asaf Karagila

291k31402732




291k31402732









asked Jul 28 at 11:11









Chandrahas Kondle

82




82







  • 1




    I would not expect either. On most clocks, by 2:42 the hour hand would be considerably beyond 2; it would be closer to 3.
    – badjohn
    Jul 28 at 11:41






  • 1




    $171^circ$ is the correct answer, unless a clearly defined oriented angle is meant, e.g., "counterclockwise from the hour hand to the minute hand".
    – Christian Blatter
    Jul 28 at 13:53










  • @ChristianBlatter, I think orientation is defined as counterclockwise. And we should measure angles in the positive direction
    – dEmigOd
    Jul 28 at 14:53












  • 1




    I would not expect either. On most clocks, by 2:42 the hour hand would be considerably beyond 2; it would be closer to 3.
    – badjohn
    Jul 28 at 11:41






  • 1




    $171^circ$ is the correct answer, unless a clearly defined oriented angle is meant, e.g., "counterclockwise from the hour hand to the minute hand".
    – Christian Blatter
    Jul 28 at 13:53










  • @ChristianBlatter, I think orientation is defined as counterclockwise. And we should measure angles in the positive direction
    – dEmigOd
    Jul 28 at 14:53







1




1




I would not expect either. On most clocks, by 2:42 the hour hand would be considerably beyond 2; it would be closer to 3.
– badjohn
Jul 28 at 11:41




I would not expect either. On most clocks, by 2:42 the hour hand would be considerably beyond 2; it would be closer to 3.
– badjohn
Jul 28 at 11:41




1




1




$171^circ$ is the correct answer, unless a clearly defined oriented angle is meant, e.g., "counterclockwise from the hour hand to the minute hand".
– Christian Blatter
Jul 28 at 13:53




$171^circ$ is the correct answer, unless a clearly defined oriented angle is meant, e.g., "counterclockwise from the hour hand to the minute hand".
– Christian Blatter
Jul 28 at 13:53












@ChristianBlatter, I think orientation is defined as counterclockwise. And we should measure angles in the positive direction
– dEmigOd
Jul 28 at 14:53




@ChristianBlatter, I think orientation is defined as counterclockwise. And we should measure angles in the positive direction
– dEmigOd
Jul 28 at 14:53










2 Answers
2






active

oldest

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up vote
0
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accepted










Here is the right image of the clock. See the angle between hour and minute hand is measured in a counterclockwise manner, hence it is more than $180^circ$.



enter image description here






share|cite|improve this answer




























    up vote
    2
    down vote













    The question asks for the angle between the hour and the minute, rather than the angle between the minute and the hour. See the diagram below for the discrepancy.



    enter image description here






    share|cite|improve this answer

















    • 1




      The figure is wrong.
      – Christian Blatter
      Jul 28 at 13:53










    • The given figure is not correct, you can see the correct clock time answered by @dEmigOd
      – Chandrahas Kondle
      Jul 30 at 17:07











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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    0
    down vote



    accepted










    Here is the right image of the clock. See the angle between hour and minute hand is measured in a counterclockwise manner, hence it is more than $180^circ$.



    enter image description here






    share|cite|improve this answer

























      up vote
      0
      down vote



      accepted










      Here is the right image of the clock. See the angle between hour and minute hand is measured in a counterclockwise manner, hence it is more than $180^circ$.



      enter image description here






      share|cite|improve this answer























        up vote
        0
        down vote



        accepted







        up vote
        0
        down vote



        accepted






        Here is the right image of the clock. See the angle between hour and minute hand is measured in a counterclockwise manner, hence it is more than $180^circ$.



        enter image description here






        share|cite|improve this answer













        Here is the right image of the clock. See the angle between hour and minute hand is measured in a counterclockwise manner, hence it is more than $180^circ$.



        enter image description here







        share|cite|improve this answer













        share|cite|improve this answer



        share|cite|improve this answer











        answered Jul 28 at 15:53









        dEmigOd

        1,2731512




        1,2731512




















            up vote
            2
            down vote













            The question asks for the angle between the hour and the minute, rather than the angle between the minute and the hour. See the diagram below for the discrepancy.



            enter image description here






            share|cite|improve this answer

















            • 1




              The figure is wrong.
              – Christian Blatter
              Jul 28 at 13:53










            • The given figure is not correct, you can see the correct clock time answered by @dEmigOd
              – Chandrahas Kondle
              Jul 30 at 17:07















            up vote
            2
            down vote













            The question asks for the angle between the hour and the minute, rather than the angle between the minute and the hour. See the diagram below for the discrepancy.



            enter image description here






            share|cite|improve this answer

















            • 1




              The figure is wrong.
              – Christian Blatter
              Jul 28 at 13:53










            • The given figure is not correct, you can see the correct clock time answered by @dEmigOd
              – Chandrahas Kondle
              Jul 30 at 17:07













            up vote
            2
            down vote










            up vote
            2
            down vote









            The question asks for the angle between the hour and the minute, rather than the angle between the minute and the hour. See the diagram below for the discrepancy.



            enter image description here






            share|cite|improve this answer













            The question asks for the angle between the hour and the minute, rather than the angle between the minute and the hour. See the diagram below for the discrepancy.



            enter image description here







            share|cite|improve this answer













            share|cite|improve this answer



            share|cite|improve this answer











            answered Jul 28 at 11:17









            Rhys Hughes

            3,8581227




            3,8581227







            • 1




              The figure is wrong.
              – Christian Blatter
              Jul 28 at 13:53










            • The given figure is not correct, you can see the correct clock time answered by @dEmigOd
              – Chandrahas Kondle
              Jul 30 at 17:07













            • 1




              The figure is wrong.
              – Christian Blatter
              Jul 28 at 13:53










            • The given figure is not correct, you can see the correct clock time answered by @dEmigOd
              – Chandrahas Kondle
              Jul 30 at 17:07








            1




            1




            The figure is wrong.
            – Christian Blatter
            Jul 28 at 13:53




            The figure is wrong.
            – Christian Blatter
            Jul 28 at 13:53












            The given figure is not correct, you can see the correct clock time answered by @dEmigOd
            – Chandrahas Kondle
            Jul 30 at 17:07





            The given figure is not correct, you can see the correct clock time answered by @dEmigOd
            – Chandrahas Kondle
            Jul 30 at 17:07













             

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