A(vec)=(2,1,-4) B(vec)=(-3,0,1) C(vec)=(-1,-1,2)(adsbygoogle = window.adsbygoogle || []).push({});

whats the angle between Avec and Bvec in rads.

i know the formula

A(vec)*B(vec)= abs(A)*abs(B)*cos(theta)

A(vec)*B(vec)=-10

so why wont cos^-1(-10/(21)(10)) work?

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# Semi math question

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