The equation for a circle is $(x-h)^2+(y-k)^2=r^2$ , where $(h,k)$ is the vertex of the circle and $r$ is the radius. Immediately, since the center of the circle is given, we know what $h$ and $k$ are. $h$ is 230 and $k$ is 220.

The only thing we need to find is the radius, which will just be the distance from the center (230,220) to a point on the circumference (170,170). The distance between them can be calculated using the <u>distance formula</u>, which is really just the <u>Pythagorean Theorem</u> rearranged. The formula states that $d=\sqrt{x^2+y^2}$ , where $x$ is the change in the x-coordinates of the two points and $y$ is the change in the y-coordinates of the two points. Plug-in $x$ for 60 and $y$ for 50 to get $d=\sqrt{50^2+60^2}$ . Solve for $d$ , arriving at $\sqrt{6100}$ . Therefore, the radius of the circle is $\sqrt{6100}$ .

Finally, we have all of the components to create the equation of the circle. Plug-in 230 for $h$ , 220 for $k$ , and $\sqrt{6100}$ for $r$ .

The equation of the circle will be $(x-230)^2+(y-220)^2=6100$ .

Hope this helps :)

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2 years ago