z_1 / z_2 = (r_1 / r_2) (cos (theta_1 - theta_2) + i sin (theta_1 - theta_2))z1z2=(r1r2)(cos(θ1−θ2)+isin(θ1−θ2))
z_1 = -9 - i, z_2 = 2 - iz1=−9−i,z2=2−i
r_1 = sqrt(-9^2 + -1^2)^2) = sqrt 82r1=√−92+−122)=√82
theta_1 = tan ^-1 (-1/ -9) ~~ 186.3402^@ = , " III Quadrant"θ1=tan−1(−1−9)≈186.3402∘=, III Quadrant
r_2 = sqrt(2^2 + (-1)^2) = sqrt 5r2=√22+(−1)2=√5
theta_2 = tan ^-1 (1/ -2) ~~ 153.4349^@, " II Quadrant"θ2=tan−1(1−2)≈153.4349∘, II Quadrant
z_1 / z_2 = sqrt(82 / 5) (cos (186.3402 - 153.4349) + i sin (186.3402 - 153.4349))z1z2=√825(cos(186.3402−153.4349)+isin(186.3402−153.4349))
color(indigo)(=> 3.4 + 2.2 i, " I Quadrant"⇒3.4+2.2i, I Quadrant