Question

Let’s consider the below geometrical layout.
1- Demonstrate that in arbitrary point “M”, the radius (r) has the expression

Answer 1

As per the information given we can say that

here M is the arbitrary point

Since figure is missing so we can assume that focal length is F for the reflector used

Now expression for r can be given as follows

Let us assume that angle between reflector and reciever be $\phi$

So,

$r=\frac{2F}{1+cos \phi}$