1. Solve the 2nd equation for t:

and plug in this term into the first equation:

This one is for you!

2) Eliminate t to give an equation that relates x and y.

x=tan(t) and y=sec^2(t)-31. Re-arrange the equation:

3) Show that this equation represents a circle by rearranging it into the centre-radius form of the equation of a circle. State the coordinates of the center and the radius of the circle:

21y^2+19x^2+83=4x-2x^2-84y

...

2. Complete the squares:

3. Divide the equation by the leading factor of the brackets on the LHS:

4. Determine the coordinates of the centre and the length of the radius.