In this video you are shown the Pythagorean identities and how they are derived. In a later tutorial you will have to prove identities using these.

Pythagorean Identities:

  • sin2θ + cos2θ ≡ 1
  • 1 + tan2θ ≡ sec2θ
  • 1 + cot2θ ≡ cosec2θ