5fg for this

sin²x - cos²x = 0, x∈[0, 2π)

nvm

This post was edited by blitzlp on Jan 15 2014 11:34am

sinsin=coscos

sin=cos
45 degrees

Where is the linear algebra question ?

sin² - cos² = 0

(sin + cos)(sin - cos) = 0

sin = cos or sin = - cos

sin x = cos x => x = pi/4 or 5*pi/4 (45° or 225°)
sin x = - cos x => x = 3*pi/4 or 7*pi/4 (135° or 315°)

given that x is in [0;2pi]