Trigonometry: polar coordinates help?

Need some help here please

1. the rectangular point are given. Find the polar coordinates (R, θ) of this point with θ expressed in radiant. Let R>0 and -2pi< θ<2pi

2. the letters X and Y represent rectangular coordinates, write the given equation using polar coordinates (r,θ)

A. 2r^2 sin (2θ)=1

B.2r^2 cos (2θ)=1

C. 4r^2 sin (2θ)=1

D. 4r^2 cos(2θ)=1

3.the letters X and Y represent rectangular coordinates, write the given equation using polar coordinates (r,θ)

A. r= 5/ cosθ + sin θ

B. r=5

C. r^2=5/ cosθ + sin θ

D. r^2=5

4. the letters r and θ represent polar coordinates. write the given equation using the rectangular coordinates (x,y)

r=8

0=?