Jawab:

garis singgung dan lingkran
i) y - b = m( x- a ) ± r√(m²+1)

i. x²  +y² = 5 ,   m = - 2
a= 0 , b = 0 ,  r = √5 , m = - 2
y - b = m( x- a ) ± r√(m² +1)
y = - 2x  + 5   atau  y = - 2x -  5

ii. x² + y² - 2x + 4y - 4 = 0 , m =  5/12
(x - 1)² + (y + 2)² =  9
a= 1 , b = -2 , r = 3 , m = 5/12

y - b = m( x- a ) ± r√(m² -1)
y +2 = 5/12( x- 1 ) ± 3√(25/144+1)
y +2 = 5/12( x- 1 ) ± 3√(169/144)
y +2 = 5/12( x- 1 ) ± 3 (13/12)
12 y + 24 = 5(x - 1)  ± 39
12y + 24 = 5x - 5  ± 39
12y = 5x - 5  - 24  ± 39
12y =  5x - 29 +  39  --> 12y =  5x + 10
12y =   5x - 29 -  39 --> 12y =  5x - 68