Find zw Leave your answer in polar form z7cos pi8 i sin pi8

Find zw. Leave your answer in polar form

z=7(cos pi/8 + i sin pi/8)

w=9(cos pi/10 + i sin pi/10)

Solution

z=7(cos(pi/8)+ i sin(pi/8)) = 7 e^{i pi/8}

w= 9(cos(pi/10)+ i sin(pi/10))=9 e^{i pi/10}

z w =63 e^{i(pi/8 + pi/10)}=63 e^i9pi/40

63(cos (9pi/40) + i sin(9pi/40))