27.8k views
3 votes
Write the equation of a circle that has a center of (-2, 1)
and a radius 3.

User Johnmcp
by
3.8k points

1 Answer

3 votes

Answer:

Explanation:

(x + 2)^2 + (y -1 )^2 = 3^2

(x + 2)^2 + (y -1)^2 = 9

I have used Desmos to draw this for you. Notice that the center is not (2, -1) but is at -2,1 just as the question requested. The signs are always reversed when the center of a circle must be obtained by squaring the numbers in parenthesis.

Further two points are shown. The one you should pay attention to is (-2,4) which is 3 units away from the center. The other point is also 3 units away, but you have to use the distance formula which you may not be familiar with. If you measure it with a ruler, you will find it is the same distance away from the center as (-2,4) is Since they are equal, they both must represent the length of the radius.

Write the equation of a circle that has a center of (-2, 1) and a radius 3.-example-1
User Brad Davis
by
4.1k points