tentukan persamaan lingkaran yang melalui titik (3,1),(-2,-4).dan 7,-1

Pusat (a, b)

(3-a)² + (1-b)² = r²
9-6a+a²+1-2b+b² = r²
a²+b²-6a-2b+10 = r²

(-2-a)²+ (-4-b)² = r²
4+4a+a²+16+8b+b² = r²
a²+b²+4a+8b+20 = r²

(7-a)² + (-1-b)² = r²
49-14a+a²+1+2b+b² = r²
a²+b²-14a+2b+50 = r²

a²+b²-6a-2b+10 = r²
a²+b²+4a+8b+20 = r²
________________ -
-10a-10b-10 = 0
a+b. = -1


a²+b²-6a-2b+10 = r²
a²+b²-14a+2b+50 = r²
________________ -
8a-4b-40 = 0
2a-b. = 10

a+b = -1
2a-b = 10
_______ +
3a. = 9
a = 3
b = -1-3
= -4

r² = (3-3)²+(1+4)²
= 5²
= 25

Pers :
(x-3)²+(y+4)² = 25
x²-6x+9+y²+8y+16-25 = 0
x²+y²-6x+8y = 0