Play with the identities
sin(540 - x) = sin(180 - x) = sinx , (540° is one rotation + 180°)
sin(-x) = sinx
cos(180-x) = -cosx
sin(90+x) = sin90cosx + cos90sinx = cosx + 0 = cosx
Sin(540-x).sin(-x) -cos(180-x).sin(90+x)
= (sinx)(sinx) - (-cosx)(cosx)
= sin^2 x + cos^2 x
= 1
Simplify to a single term
Sin(540-x).sin(-x) -cos(180-x).sin(90+x)
1 answer