What is the equation of a circle with center (9, -11) and the point (12, -15) on its circumfance

(x - 9)^2 + (y + 11)^2 = 25.

Step-by-step explanation:

First find the radius which is the distance between the center and the point on the circumference:

Radius =  √ [( -15 - (-11))^2 + (12 - 9)^2)]

= √(16 + 9)

= 5.

The equation of a circle can be written as:

(x - h)^2 + (y - k)^2 = r^2  where (h, k) is the centre and r is the radius.

So here we have:

(x - 9)^2 + (y + 11)^2 = 5^2.

13

step-by-step explanation:

169-1=168

168-3=165

165-5=160

160-7=153

153-9=144

144-11=133

133-13=120

120-15=105

105-17=88

88-19=69

69-21=48

48-23=25

25-25=0

since it took 13times to completely subtract it hence its square root is 13