Question

The focal distance of the point (9, 6) on the parabola $y^2=4x$ is

• A. 4
• B. 8
• C. 10
• D. 16

Answer 1

The correct option is C 10

$y^2=4x\Rightarrow 4a=4\Rightarrow a=1Focus=S=(a,0)=(1,0),P(9,6)\therefore Focaldistance=SP=\sqrt{(9-1{)}^2+(6-0{)}^2}=\sqrt{64+36}=10$