# What is the angle between <7 , 3 , -3 >  and  < 8 , 6 , 8 > ?

Apr 15, 2016

$\theta \approx {61.51}^{\circ}$

#### Explanation:

Use formula
$\cos \theta = \frac{a \cdot b}{| a | | b |}$

cos theta=(<7,3,-3>*<8,6,8>)/(sqrt(7^2+3^2+(-3)^2)sqrt(8^2+6^2+8^2)

$\cos \theta = \frac{56 + 18 - 24}{\sqrt{67} \sqrt{164}}$

costheta=50/(sqrt10988

$\theta = {\cos}^{-} 1 \left(\frac{50}{\sqrt{10988}}\right)$

$\theta \approx {61.51}^{\circ}$