Question

Simplifique: sen ( pi/2+x )

Answer 1

a) sen (pi/2 + x) = (sen pi/2)(cos x) + (sen x)(cos pi/2)
sen (pi/2 + x) = 1.cos x + (sen x).0    
sen (pi/2 + x) = cos x

b) cos (3pi/2 - x) = (cos 3pi/2)(cos x) + (sen 3pi/2)(sen x)
cos (3pi/2 - x) = 0.cos x + (-1).sen x
cos (3pi/2 - x) = - sen x