CPM Homework Help : PC3 Problem 10-147

Calculate the angle between each pair of vectors.

$⟨2,3⟩$ , $⟨1,4⟩$
Hint:
$\cos(\theta)=\frac{\vec{u}\cdot \vec{v}}{||\vec{u}||\cdot ||\vec{v}||}$
Step (a):
$\cos(\theta)=\frac{2(1)+3(4)}{\sqrt{2^2+3^2}\cdot\sqrt{1^2+4^2}}$