tentukan persamaan garis singgung pada lingkaran x²+y²-2x+4y-4=0 yang sejajar dengan 5x-12y+15=0

A=-2 B=4 C=-4
O(a,b) = (-A/2, -B/2) = (1,-2)
r = √a2+b²-C = √1+4-(4) = √9 = 3
Gradien : m = -5/-12 = 5/12, karena sejajar maka m = m1.

y-b = m(x-a) ± r√m1²+1
y+2 = 5/12(x-1) ± 3√(5/12)² + 1
y+2 = 5/12x - 5/12 ± 3√169/144

1) y = 5/12x -5/12 - 2 + 39/12
y = 5/12x + 10/12
12y = 5x + 10
5x - 12y + 10 = 0

2) y = 5/12x - 5/12 - 2 - 39/12
y = 5/12x - 68/12
12y = 5x - 68
5x-12y-68 = 0