Question

The equation of a parabola is $x^2=-10y,$ then coordinates of focus are

• A. $\left(0,-\frac{5}{2}\right)$
• B. $\left(0,\frac{5}{2}\right)$
• C. $\left(\frac{5}{2},0\right)$
• D. $\left(-\frac{5}{2},0\right)$

Answer 1

Answer: (A)

Equation of parabola is
$x^2=-10y$
On comparing with
$x^2=-4ay$ we get $-4a=-10$ or $a=\frac{10}{4}=\frac{5}{2}$
Hence, coordinates of focus $=(0,-5/2)$