27.4.5 Finding Length and Angle with the Dot Product
27.4 The Dot Product: Angles and Perpendicularity
Point 5 of 7
27.4.5 Finding Length and Angle with the Dot Product
Core idea
Dot a vector with itself and take the square root to get its length, |a|=√(a·a); then rearrange the cosθ formula to recover the angle.
Module goal. Introduce the operation that multiplies two vectors into a number, capturing the angle between them, projection, and when they're perpendicular.
eastmath.com · 27.4 The Dot Product: Angles and Perpendicularity · 27.4.5 Finding Length and Angle with the Dot Product