Need Help with math

[Mirinee]

Lines with equal slopes are parallel to each other; lines with negative reciprocals are perpendicular.

Not to each other. You mean a line with gradient m is perpendicular to a line with gradient -1/m.

Eep. Converting from polar and rectangular. Um...
I hope the ones you get given are no more difficult than the example you gave.

R=cos(theta) on the polar graph (plot it ) is a circle of radius 1, its left side touching the origin, *draws*, so just look at that and say, oh, use the cartesian "equation of a circle", which is of the form
((X-A)^2)+((Y-B)^2) = C^2 , like whiteninja said.
The centre would be (0.5, 0), and its radius is 1, hence

(X-0.5)^2 + Y^2 = 1.

This might be a clumsy way of doing it, but I can't think of another way off the top of my head right now ;;^_^ .

I hope you won't be given anything other than
-equation of a straight line
-equation of a parabola
-equation of a circle