+128454 a) (-4, 4)
r = sqrt [ (-4)^2 + 4^2] = sqrt [32] = 4sqrt (2)
θ = arctan (4/-4) = arctan (-1) = -pi/ 4 ....this is a point in te second quadrant so θ = -pi/4 + pi =
3pi/4
So (r, θ) = ( 4sqrt 2, 3pi/4)
(b) x^2 + (y - 5)^2 = 25 expand
x^2 + y^2 - 10y + 25 = 25 subtract 25 from both sides
x^2 + y^2 - 10y = 0
r^2cos^2θ + r^2sin^2θ - 10 ( r sinθ) = 0
r^2 ( cos^2θ + sin^2θ) = 10r (sin θ)
r^2 (1) = 10r (sin θ) divide out r
r = 10sinθ
