A circle is centered at the point (-3,2) and passes through the point (1,5). the radius of the circle is ___ units. The point (-7,__) lies on the circle.

Question

Using coordinates to prove geometric theorems

Answer 1

The equation of the circle with center at the point (-3, 2) is 

(x+3)²+(y-2)²=R². This  circle passes through the point (1, 5), that is,

(1+3)²+(5-2)²=R². So, R² =4²+3²=16+9=25.  

The radius of the circle is 5.

 

 

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