The focal distance of a point on the parabola `y^2= 16x` whose ordinate is twice the abscis is

Options

A. 6
B. 8
C. 10
D. 12

Answer

B

Explanation

Given, cure is `y^(2)=16x. Let any point on it be (h,k) but `2h=k and k^(2)=16h`
`rArr 4h^(2)=16hrArrh=0,h=4`
rArr k=0, k=8 `
`therefore` are (0,0),(4,8). Hence, focal distance are respectively o+4=4 and 4+4=8[therefore` focal distance=h+a]