What is the angle between <6,9,2> and <2,0,4>?

1 Answer
Dec 12, 2015

θ=arccosax+by+czx2+y2+z2a2+b2+c2

Explanation:

There are many multiplicities of this question, so let me solve all of them.

v=(x,y,z)

w=(a,b,c)

vw=|v||w|cosθ

ax+by+cz=x2+y2+z2a2+b2+c2cosθ

What is left is your arithmetical hability!

128=36+81+44+16cosθ

201120=cosθ=2011