Trigonometry

Pythagorean Identities

sin²x + cos²x = 1 and others

  • High school
  • about 3 min
  • 7 of 11 in the family
Not started
cos=0.766sin=0.6431cos² = 0.587sin² = 0.413sum = 1.000000
θ = 40°
sin⁡2θ+cos⁡2θ=0.64282+0.76602=1.000000\sin^2\theta + \cos^2\theta = 0.6428^2 + 0.7660^2 = 1.000000
1+ an2 heta=sec⁡2 heta1 + \ an^2\ heta = \sec^2\ heta

sin²θ+cos²θ=1 is the Pythagorean theorem on the unit circle: the legs are cos θ and sin θ, the hypotenuse = radius = 1. True for EVERY angle.

Where it is taught