- #1
Tarrok
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Homework Statement
Two vectors A and B have magnitude A = 3.00 and B = 3.00. Their vector product is A x B= -5.00k + 2.00i. What is the angle between A and B?
Homework Equations
Magnitude of vector product = magnitude of A * magnitude of B * sin of the smaller angle between A and B
|C|=|A||B|*sinX
The Attempt at a Solution
|C|=(5^2+2^2)^(1/2)=3*3*sinX
sinX=(5^2+2^2)^(1/2)/9
X = arcsin[(5^2+2^2)^(1/2)/9]=36.75 degrees
According to the answer, the angle is 37 degrees. As shown above, I see where this comes from. However, we know that sin(36,75)=sin(143,25).
So the magnitude of vector C, where vector C is the cross product of vectors A and B is
3*3sin(36,75)=3*3sin(143,25)=5,385
My question is:
Why is 37 degrees the only correct answer if 143 degrees also works?
Thanks for help