MatsGO
All trainers
MatsGO
All trainers
sin, cos, tan — key identities, addition and double-angle formulas, and practice trainer.
sin²α + cos²α = 1. This is the fundamental trigonometric identity, valid for any angle α.
sin 2α = 2 sin α cos α; cos 2α = cos²α − sin²α = 1 − 2sin²α = 2cos²α − 1.
sin(α+β) = sin α cos β + cos α sin β; cos(α+β) = cos α cos β − sin α sin β.