Question 430780
Using the addition formula for cosine:


{{{cos(3pi/2 + x) = cos(3pi/2)cos(x) - sin(3pi/2)sin(x)}}} Since {{{cos(3pi/2) = 0}}} and {{{sin(3pi/2) = -1}}},


{{{cos(3pi/2 + x) = 0*cos(x) - (-1)(sin(x))}}}


= {{{sin(x)}}}.