sin = SCCS (same sign) cos = CCSS (diff. sign)
Pythagorean Identities (Main Identity)
cos2x + sin2x = 1
Pythagorean Identities (In terms of tan x)
**divide by cos
1 + tan2x = sec2x
Pythagorean Identities (In terms of cos x)
**divide by sin
1 + cot2x = csc2x
Sin sum Identity
sin(a + B) = sin a cos B + cos a sin B
Cos sum identity
cos(a + B) = cos a cos B - sin a sin B
Sin difference identity
sin ( a - B) = sin a cos B - cos a sin B
cos difference identities
cos (a - B) = cos a cos B + sin a sin B
sin double agent identities
sin(2b) = 2sin b cos b
cos double agent identities
cos(2b) = cos2b - sin2b OR
1 - 2 sin2b OR
2cos2b - 1