Answer to Question #139917 in Trigonometry for Michael

Question

Use the appropriate compound angle formula to create an equivalent expression

a) cos ( x+3pi over 2 )
b) sin ( pi + x )

Answer 1

a)cos(x+3π/2)

= cosx*cos3π/2 - sinx*sin3π/2

=cosx•0 - six•(-1)

=0 - (-sinx)

=sinx

b) sin(π+x)

= sinπ*cosx+cosπ*sinx

=0•cosx +( -1)•sinx

=0-sinx

=-sinx