Question

The focal distance of a point on the parabola $y^2=8x$ is 10. Its coordinates are

• A. (2,±2)
• B. (3,±3)
• C. (5,±5)
• D. (8,±8)

Answer 1

The correct option is D

(8,±8)

$y^2=8x4a=8\Rightarrow a=2$
$x_1+a=10$
$\Rightarrow x_1=8y_1^2=8\times 8=8^2\Rightarrow y_1=\pm 8$
$\left(x_1{y}_1\right)=(8,\pm 8)$