Find the quotient z1/z2

Question

z1=21(cos260°+isin260°) and z2=3(cos170°+isin170°)

Answer 1

z1=21(cos260°+isin260°) = 21(-sin10 - icos10) = -21(sin 10 + i Cos10)

z2=3(cos170°+isin170°)= 3(-cos 10 +i sin10)

z1/z2= (-21 (sin 10 + i Cos10))/(-3(cos 10 - i sin10))

multiply numerator and denominator by (cos 10 - i sin10)

z1/z2= 7 (sin 10 cos 10 +i sin² 10 +i cos² 10 +i² sin10 cos 10) = 7i