Find the cartesian coordinates

If (x,y) = (-3,8) then (r,theta) = ?

I already got r it is -sqrt73 but i cant seem to get theta right.
I got 110.556 but its wrong...please tell me how to do it thank you!!

3 answers

x = - 3 , y = 8

QUADRANT II

arc tan ( sqrt 73 ) = 83.324408°

tan ( theta ) = - sqrt ( 73 )

theta = 180 ° - 83.324408°

theta = 96.675592°

theta = 96° 40' 32"
I don't agree with the above Ø

r = √(x^2+y^2)= √73

angle in standard position = arctan(8/3) = 69.44°

since (-3,8) is in II
Ø = 180-69.44 = 110.56°

(-3,8) ----> (√73, 110.56°)
Both of these answers are still wrong