Graphs Of Circles
Lesson 1
Problem:  Write the equation of a circle that has a center at (-2, 4) and a radius of 2?
Step 1:

The equation of a Circle is: (x - h)2 + (y - k)2 = r2;

 

where coordinate of the center of the circle is (h, k) and r is radius.   

Step 2:
The equation of given circle is [x - (-2)] 2 + (y - 4)2 = (2)2;
Step 3:
The answer is:  (x +2)2 + (y - 4)2 = 4
 
Try two practice problems. Do the following:
A. Write the equation of a circle whose diameter is 16 and whose center is at (2, 8)? 
 
B. What are the coordinates of the center of this circle? (x + 5)2 + (y - 7)2 = 25.
                                                                               

                                     

 

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