Given: circle passes through (−1,0)
and touches the y-axis at (0,2)
To find: which point also lies on the circle
A(−1,0),T(0,2)
At T: radius⊥tangent (the y-axis)
⇒centre O=(h,2),r=∣h∣
OA2=(h+1)2+(2−0)2=r2=h2
h2+2h+5=h2 ⇒ 2h+5=0
h=−25
O(−25,2),r=25
(x+25)2+(y−2)2=425
(x+25)2+(y−2)2=425 ⇒ x2+y2+5x−4y+4=0
hline Point x²+y²+5x-4y+4 On circle?
hline (-3/2,0) -5/4 ×
(-5/2,2) -25/4 ×
(-3/2,5/2) -5 ×
(-4,0) 0 checkmark
hline
Answer: (−4,0) — option (4)