Posted by **Nikki** on Tuesday, April 10, 2007 at 11:57pm.

Ok, I have two questions first:

1. I'm asked to find a cartesian equation for the polar graph of this polar equation: r^2 = sin(2(theta))

The answer I got was

(x^2+y^2)^2/(2xy) = 2

Is this the correct way to express it?

2. I need to find the cartesian equation for this parametric equation:

x = sec(t) + tan(t)

y = sec(t) - tan(t)

I have tried using the identity tan^2x + 1 = sec^2x, but I feel like I'm moving in circles!

I'd appreciate it so much if someone could help me!!! Thanks =)

2. x + y = 2 sec t

x - y = 2 tan t

(1/4)(x+y)^2 = (1/4)(x-y)^2 + 1

This gets rid of the t terms. Rearrange and simplify.