I really need some help with figuring out the following problems

1. The letters r and represent polar coordinates. Write the following equation using rectangular coordinates (x, y). r=sin
2. The letters x and y represent rectangular coordinates. Write the following equation using polar coordinates (r, ). x=5
3. Convert the rectangular coordinates (-8,i3) into complex polar coordinates.
4. The letters x and y represent rectangular coordinates. Write the following equation using polar coordinates (r, ). x^2+y^2=1