Pythagorean identity

4 videos
2 skills
In this tutorial, we look at the relationship between the definitions of sine, cosine and tangent (both SOH CAH TOA and unit circle definitions) and the Pythagorean theorem to derive and apply the Pythagorean identity. This is the building block of much of the rest of the trigonometric identities and will be surprisingly useful the rest of your life!

Pythagorean trig identity from soh cah toa

VIDEO 4:16 minutes

Pythagorean trig identity from unit circle

VIDEO 6:12 minutes

Using the Pythagorean trig identity

VIDEO 6:15 minutes

Circles and Pythagorean identities

PRACTICE PROBLEMS

Examples using pythagorean identities to simplify trigonometric expressions

VIDEO 3:07 minutes

Manipulating trig expressions with pythagorean identities

PRACTICE PROBLEMS
Simplify expressions using Pythagorean trig identities