You need two equations to solve a two-variable equation.
Answer:

Step-by-step explanation:
The radius is the distance between the center and any point on the circle.
The formula of a distance between two points:

We have the center (3, -3) and other point on the circle (7, 6).
Substitute:

Answer:
The width which gives the greatest area is 7.5 yd
Step-by-step explanation:
This is an application of differential calculus. Given the area as a function of the width, we simply need to differentiate the function with respect to x and equate to zero which yields; 15-2x=0 since the slope of the graph is zero at the turning points. Solving for x yields, x=7.5 which indeed maximizes the area of the pen
Answer:
An adorable kitten!
Step-by-step explanation: