### Home > PC3 > Chapter 10 > Lesson 10.2.3 > Problem10-147

10-147.

Calculate the angle between each pair of vectors.

1. $⟨2, 3⟩, ⟨1, 4⟩$

$\cos(\theta)=\frac{\vec{u}\cdot \vec{v}}{||\vec{u}||\cdot ||\vec{v}||}$

$\cos(\theta)=\frac{2(1)+3(4)}{\sqrt{2^2+3^2}\cdot\sqrt{1^2+4^2}}$

1. $⟨−1, 2⟩, ⟨6, 1⟩$