# Math

Find the angle Q between the two vectors.

u = 10i + 40j v = -3j+8k

cos <10,40,0> <0,-3,8> / sqrt1700 sqrt73

cos(-120/sqrt1700 sqrt73) = .9072885394

arc cos (.9072885394) = 24.86 degrees.

Is this correct?

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1. somewhere in your calculations I can see the dot product, but your terminology is not familiar to me
Also the statement
cos(-120/sqrt1700 sqrt73) = .9072885394
makes little sense

Here is how i would set it up
u = [10,40,0] and v = [0,-3,8]

u•v = |u||v|cos Ø
-120 = √1700√73 cos Ø
cos Ø = -120/(√1700√73) = -.3406398
(you did not have that)
Ø = arccos(-.3406398) = 109.9°

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posted by Reiny

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