### Home > A2C > Chapter 9 > Lesson 9.1.2 > Problem 9-44

9-44.

A circle with its center on the line

*y*= 3*x*in the 1^{st}quadrant is tangent to the*y*-axis. Homework Help ✎If the radius is 2, what is the equation of the circle?

If the radius is 3, what is the equation of the circle?

Try sketching the circle. The circle to the right has a radius of 2. Try placing it on the axis so it matches the circle described in the problem. The line *y* = 3*x* has been graphed for you.

Use the coordinates of the center and the radius to write an equation in general form.

(*x* − 2)^{2} + (*y* − 6)^{2} = 4

See part (a).

(*x* − 3)^{2} + (*y* − 9)^{2} = 9

Use the eTool below to explore the problem further.

Click the link at right for the full version of the eTool: A2C 9-44 HW eTool