I cant figure this out I understand the r but cant find thet

I can\'t figure this out! I understand the r but can\'t find theta... I got -1.279 but that\'s wrong

For each complex number, determine the angle and the length r.

y=-3+10i ry=10.440 thetay= ????

Solution

As the components of y are not clearly written. Consider it as

y =10i - 3j

Then r_y = sqrt[100 + 9] = 10.440

Theta_y = arctan(-3/10) = arctan(-0.3) = -16.7 degree = -0.2915 rad

Now check plz.