If (7, m) is on a circle with center C(-2, 2) and radius 9, what is the value of m?

Question

If (7, m) is on a circle with center C(−2, 2) and radius 9, what is the value of m? the choices are 

a.m=2

b.m=-2+√65

c.m=-2

d.m=-2+√2

Answer 1

An equation of the circle with center (h,k) and radius r is                              (x-h)²+(y-k)²=r²

 

So, we have (x+2)²+(y-2)²=81

 

   Since (7,m) is on the circle, (7+2)²+(m-2)²=81

 

                                              81 + (m-2)²=81

 

                                                     (m-2)²=0

 

                                                         m = 2