Angle between vectors $vec a + vec b$ and $vec c$?
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If there are three vector $vec a$, $vec b$ and $vec c$ provided, what is the angle between $vec a + vec b$ and $vec c$? I understand how to calculate for angle between $vec a$ and $vec b$, $vec a$ and $vec c$ and $vec b$ and $vec c$ but what does the angle between $vec a + vec b$ and $vec c$ mean?
vectors inner-product-space
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up vote
2
down vote
favorite
If there are three vector $vec a$, $vec b$ and $vec c$ provided, what is the angle between $vec a + vec b$ and $vec c$? I understand how to calculate for angle between $vec a$ and $vec b$, $vec a$ and $vec c$ and $vec b$ and $vec c$ but what does the angle between $vec a + vec b$ and $vec c$ mean?
vectors inner-product-space
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
If there are three vector $vec a$, $vec b$ and $vec c$ provided, what is the angle between $vec a + vec b$ and $vec c$? I understand how to calculate for angle between $vec a$ and $vec b$, $vec a$ and $vec c$ and $vec b$ and $vec c$ but what does the angle between $vec a + vec b$ and $vec c$ mean?
vectors inner-product-space
If there are three vector $vec a$, $vec b$ and $vec c$ provided, what is the angle between $vec a + vec b$ and $vec c$? I understand how to calculate for angle between $vec a$ and $vec b$, $vec a$ and $vec c$ and $vec b$ and $vec c$ but what does the angle between $vec a + vec b$ and $vec c$ mean?
vectors inner-product-space
edited 8 mins ago
Jyrki Lahtonen
104k12160355
104k12160355
asked 19 hours ago
bison72
152
152
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add a comment |Â
5 Answers
5
active
oldest
votes
up vote
7
down vote
You compute the sum of $a+b$, that is a vector, if it helps, you can give a new name, $d$.
Now you can compute the angle between $d$ and $c$ using the formula that you are familiar with.
add a comment |Â
up vote
7
down vote
We have that $vec d=vec a+vec b$ then
$$cos (theta)=fracvec d cdot vec c$$
add a comment |Â
up vote
3
down vote
The important concept to keep in mind here is that when you add two vectors, $vec a$ and $vec b$, the result is just another vector. It has a magnitude, a direction (if its magnitude is positive), and components just like any other vector.
We may write the expression
$vec a + vec b$
in order to name this vector, but that does not make it into any new kind of object.
The formulas that apply to other vectors still apply.
To find the angle between $vec a + vec b$ and $vec c,$
take the formula you would use for the angle between any two vectors, put $vec a + vec b$
in the places where the first vector occurs in the formula,
and put $vec c$ in the places where the second vector occurs.
Look at other answers for details of what happens after you do this.
1
If vectors a=[1,1,0], b=[3,2,1], and c=[1,0,2], does the mean the angle between a +b and c will be the angle between [4,3,1] and [1,0,2]?
â bison72
14 hours ago
1
@bison72 yes, this is how vector addition works.
â Paà Âlo Ebermann
9 hours ago
add a comment |Â
up vote
2
down vote
Using the definition of the scalar product we get
$$
(a+b)cdot c =
lVert a+b rVert lVert c rVert cos angle(a+b,c)
$$
where $lVert v rVert = sqrtvcdot v$.
For non-zero $a+b$ and $c$ we can solve for the angle
$$
angle(a+b,c) = arccos frac(a+b)cdot clVert a+b rVert lVert c rVert
$$
add a comment |Â
up vote
2
down vote
Just $$cos(widehatveca+vecb,vecc)=frac(veca+vecb)vecc.$$
Here, $|veca+vecb|=sqrt$ and $(veca+vecb)vecc=vecavecc+vecbvecc.$
Why someone down voted?
â Michael Rozenberg
14 hours ago
Might be because someone thought it's not obvious that e.g. $ab$ is the scalar product of vectors and not simple product of their norms (because you've dropped the arrows used by the OP). But that's just my guess.
â Ruslan
8 hours ago
@Ruslan But there is a context. Thank you for your trying! I'll fix it.
â Michael Rozenberg
1 hour ago
add a comment |Â
5 Answers
5
active
oldest
votes
5 Answers
5
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
7
down vote
You compute the sum of $a+b$, that is a vector, if it helps, you can give a new name, $d$.
Now you can compute the angle between $d$ and $c$ using the formula that you are familiar with.
add a comment |Â
up vote
7
down vote
You compute the sum of $a+b$, that is a vector, if it helps, you can give a new name, $d$.
Now you can compute the angle between $d$ and $c$ using the formula that you are familiar with.
add a comment |Â
up vote
7
down vote
up vote
7
down vote
You compute the sum of $a+b$, that is a vector, if it helps, you can give a new name, $d$.
Now you can compute the angle between $d$ and $c$ using the formula that you are familiar with.
You compute the sum of $a+b$, that is a vector, if it helps, you can give a new name, $d$.
Now you can compute the angle between $d$ and $c$ using the formula that you are familiar with.
answered 19 hours ago
Siong Thye Goh
76.3k124592
76.3k124592
add a comment |Â
add a comment |Â
up vote
7
down vote
We have that $vec d=vec a+vec b$ then
$$cos (theta)=fracvec d cdot vec c$$
add a comment |Â
up vote
7
down vote
We have that $vec d=vec a+vec b$ then
$$cos (theta)=fracvec d cdot vec c$$
add a comment |Â
up vote
7
down vote
up vote
7
down vote
We have that $vec d=vec a+vec b$ then
$$cos (theta)=fracvec d cdot vec c$$
We have that $vec d=vec a+vec b$ then
$$cos (theta)=fracvec d cdot vec c$$
answered 19 hours ago
gimusi
63.4k73379
63.4k73379
add a comment |Â
add a comment |Â
up vote
3
down vote
The important concept to keep in mind here is that when you add two vectors, $vec a$ and $vec b$, the result is just another vector. It has a magnitude, a direction (if its magnitude is positive), and components just like any other vector.
We may write the expression
$vec a + vec b$
in order to name this vector, but that does not make it into any new kind of object.
The formulas that apply to other vectors still apply.
To find the angle between $vec a + vec b$ and $vec c,$
take the formula you would use for the angle between any two vectors, put $vec a + vec b$
in the places where the first vector occurs in the formula,
and put $vec c$ in the places where the second vector occurs.
Look at other answers for details of what happens after you do this.
1
If vectors a=[1,1,0], b=[3,2,1], and c=[1,0,2], does the mean the angle between a +b and c will be the angle between [4,3,1] and [1,0,2]?
â bison72
14 hours ago
1
@bison72 yes, this is how vector addition works.
â Paà Âlo Ebermann
9 hours ago
add a comment |Â
up vote
3
down vote
The important concept to keep in mind here is that when you add two vectors, $vec a$ and $vec b$, the result is just another vector. It has a magnitude, a direction (if its magnitude is positive), and components just like any other vector.
We may write the expression
$vec a + vec b$
in order to name this vector, but that does not make it into any new kind of object.
The formulas that apply to other vectors still apply.
To find the angle between $vec a + vec b$ and $vec c,$
take the formula you would use for the angle between any two vectors, put $vec a + vec b$
in the places where the first vector occurs in the formula,
and put $vec c$ in the places where the second vector occurs.
Look at other answers for details of what happens after you do this.
1
If vectors a=[1,1,0], b=[3,2,1], and c=[1,0,2], does the mean the angle between a +b and c will be the angle between [4,3,1] and [1,0,2]?
â bison72
14 hours ago
1
@bison72 yes, this is how vector addition works.
â Paà Âlo Ebermann
9 hours ago
add a comment |Â
up vote
3
down vote
up vote
3
down vote
The important concept to keep in mind here is that when you add two vectors, $vec a$ and $vec b$, the result is just another vector. It has a magnitude, a direction (if its magnitude is positive), and components just like any other vector.
We may write the expression
$vec a + vec b$
in order to name this vector, but that does not make it into any new kind of object.
The formulas that apply to other vectors still apply.
To find the angle between $vec a + vec b$ and $vec c,$
take the formula you would use for the angle between any two vectors, put $vec a + vec b$
in the places where the first vector occurs in the formula,
and put $vec c$ in the places where the second vector occurs.
Look at other answers for details of what happens after you do this.
The important concept to keep in mind here is that when you add two vectors, $vec a$ and $vec b$, the result is just another vector. It has a magnitude, a direction (if its magnitude is positive), and components just like any other vector.
We may write the expression
$vec a + vec b$
in order to name this vector, but that does not make it into any new kind of object.
The formulas that apply to other vectors still apply.
To find the angle between $vec a + vec b$ and $vec c,$
take the formula you would use for the angle between any two vectors, put $vec a + vec b$
in the places where the first vector occurs in the formula,
and put $vec c$ in the places where the second vector occurs.
Look at other answers for details of what happens after you do this.
answered 17 hours ago
David K
48k339106
48k339106
1
If vectors a=[1,1,0], b=[3,2,1], and c=[1,0,2], does the mean the angle between a +b and c will be the angle between [4,3,1] and [1,0,2]?
â bison72
14 hours ago
1
@bison72 yes, this is how vector addition works.
â Paà Âlo Ebermann
9 hours ago
add a comment |Â
1
If vectors a=[1,1,0], b=[3,2,1], and c=[1,0,2], does the mean the angle between a +b and c will be the angle between [4,3,1] and [1,0,2]?
â bison72
14 hours ago
1
@bison72 yes, this is how vector addition works.
â Paà Âlo Ebermann
9 hours ago
1
1
If vectors a=[1,1,0], b=[3,2,1], and c=[1,0,2], does the mean the angle between a +b and c will be the angle between [4,3,1] and [1,0,2]?
â bison72
14 hours ago
If vectors a=[1,1,0], b=[3,2,1], and c=[1,0,2], does the mean the angle between a +b and c will be the angle between [4,3,1] and [1,0,2]?
â bison72
14 hours ago
1
1
@bison72 yes, this is how vector addition works.
â Paà Âlo Ebermann
9 hours ago
@bison72 yes, this is how vector addition works.
â Paà Âlo Ebermann
9 hours ago
add a comment |Â
up vote
2
down vote
Using the definition of the scalar product we get
$$
(a+b)cdot c =
lVert a+b rVert lVert c rVert cos angle(a+b,c)
$$
where $lVert v rVert = sqrtvcdot v$.
For non-zero $a+b$ and $c$ we can solve for the angle
$$
angle(a+b,c) = arccos frac(a+b)cdot clVert a+b rVert lVert c rVert
$$
add a comment |Â
up vote
2
down vote
Using the definition of the scalar product we get
$$
(a+b)cdot c =
lVert a+b rVert lVert c rVert cos angle(a+b,c)
$$
where $lVert v rVert = sqrtvcdot v$.
For non-zero $a+b$ and $c$ we can solve for the angle
$$
angle(a+b,c) = arccos frac(a+b)cdot clVert a+b rVert lVert c rVert
$$
add a comment |Â
up vote
2
down vote
up vote
2
down vote
Using the definition of the scalar product we get
$$
(a+b)cdot c =
lVert a+b rVert lVert c rVert cos angle(a+b,c)
$$
where $lVert v rVert = sqrtvcdot v$.
For non-zero $a+b$ and $c$ we can solve for the angle
$$
angle(a+b,c) = arccos frac(a+b)cdot clVert a+b rVert lVert c rVert
$$
Using the definition of the scalar product we get
$$
(a+b)cdot c =
lVert a+b rVert lVert c rVert cos angle(a+b,c)
$$
where $lVert v rVert = sqrtvcdot v$.
For non-zero $a+b$ and $c$ we can solve for the angle
$$
angle(a+b,c) = arccos frac(a+b)cdot clVert a+b rVert lVert c rVert
$$
edited 18 hours ago
answered 18 hours ago
mvw
30.1k22150
30.1k22150
add a comment |Â
add a comment |Â
up vote
2
down vote
Just $$cos(widehatveca+vecb,vecc)=frac(veca+vecb)vecc.$$
Here, $|veca+vecb|=sqrt$ and $(veca+vecb)vecc=vecavecc+vecbvecc.$
Why someone down voted?
â Michael Rozenberg
14 hours ago
Might be because someone thought it's not obvious that e.g. $ab$ is the scalar product of vectors and not simple product of their norms (because you've dropped the arrows used by the OP). But that's just my guess.
â Ruslan
8 hours ago
@Ruslan But there is a context. Thank you for your trying! I'll fix it.
â Michael Rozenberg
1 hour ago
add a comment |Â
up vote
2
down vote
Just $$cos(widehatveca+vecb,vecc)=frac(veca+vecb)vecc.$$
Here, $|veca+vecb|=sqrt$ and $(veca+vecb)vecc=vecavecc+vecbvecc.$
Why someone down voted?
â Michael Rozenberg
14 hours ago
Might be because someone thought it's not obvious that e.g. $ab$ is the scalar product of vectors and not simple product of their norms (because you've dropped the arrows used by the OP). But that's just my guess.
â Ruslan
8 hours ago
@Ruslan But there is a context. Thank you for your trying! I'll fix it.
â Michael Rozenberg
1 hour ago
add a comment |Â
up vote
2
down vote
up vote
2
down vote
Just $$cos(widehatveca+vecb,vecc)=frac(veca+vecb)vecc.$$
Here, $|veca+vecb|=sqrt$ and $(veca+vecb)vecc=vecavecc+vecbvecc.$
Just $$cos(widehatveca+vecb,vecc)=frac(veca+vecb)vecc.$$
Here, $|veca+vecb|=sqrt$ and $(veca+vecb)vecc=vecavecc+vecbvecc.$
edited 1 hour ago
answered 19 hours ago
Michael Rozenberg
86.9k1575178
86.9k1575178
Why someone down voted?
â Michael Rozenberg
14 hours ago
Might be because someone thought it's not obvious that e.g. $ab$ is the scalar product of vectors and not simple product of their norms (because you've dropped the arrows used by the OP). But that's just my guess.
â Ruslan
8 hours ago
@Ruslan But there is a context. Thank you for your trying! I'll fix it.
â Michael Rozenberg
1 hour ago
add a comment |Â
Why someone down voted?
â Michael Rozenberg
14 hours ago
Might be because someone thought it's not obvious that e.g. $ab$ is the scalar product of vectors and not simple product of their norms (because you've dropped the arrows used by the OP). But that's just my guess.
â Ruslan
8 hours ago
@Ruslan But there is a context. Thank you for your trying! I'll fix it.
â Michael Rozenberg
1 hour ago
Why someone down voted?
â Michael Rozenberg
14 hours ago
Why someone down voted?
â Michael Rozenberg
14 hours ago
Might be because someone thought it's not obvious that e.g. $ab$ is the scalar product of vectors and not simple product of their norms (because you've dropped the arrows used by the OP). But that's just my guess.
â Ruslan
8 hours ago
Might be because someone thought it's not obvious that e.g. $ab$ is the scalar product of vectors and not simple product of their norms (because you've dropped the arrows used by the OP). But that's just my guess.
â Ruslan
8 hours ago
@Ruslan But there is a context. Thank you for your trying! I'll fix it.
â Michael Rozenberg
1 hour ago
@Ruslan But there is a context. Thank you for your trying! I'll fix it.
â Michael Rozenberg
1 hour ago
add a comment |Â
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