Question

The sun(diameter d) subtends an angle $\theta$ radian at the pole of a concave mirror of focal length f. The diameter of the image of the sun formed by a mirror is?

Answer 1

We see $v=f$

We have$\theta$ in radian

$\frac{x}{f}=tan\theta$

$x=ftan\theta$

$x=f\theta$

Thus the diameter of sun is$2x$ $2f\theta$