The radius of the circle is 17 uints and the point (-15,-16) or (-15,14) lies on the circle.
step by step explanation is here,
centre of circle(h,k)=(-7,-1)
if the circle passes through the point (8,7)
then the distance between (8,7) and (-7,-1) represents the radius.
so, r^2= (x2-x1)^2 + (y2-y1)^2
or, r^2=(-7-8)^2 +(-1-7)^2
or, r^2=(-15)^2 +(-8)^2
or, r^2=225+64
or, r^2=289
or, r=17 units
now the equation of circle is
(x-h)^2 +(y-k)^2 =r^2
or, (x+7)^2 +(y+1)^2 =289
or, x^2 +14x +49 + y^2 + 2y+ 1=289
or, x^2 + y^2 + 14x +2y-239=0
puttimg x=-15,
or, (-15)^2 + y^2 +14×(-15) + 2y -239=0
or, y^2 + 2y -239+225-210=0
or, y^2 + 2y -224=0
If you slove y, then you will get 14 and -16.
