Show that area of circular patch of light on water as seen from a water medium is `A=pi h^(2)//(n^(2)-1)` where symbols haves their usual meaning.

Explanation

`tanC=(1)/(sqrt(n^(2)-1))`
`and tanC=(r)/(h)`
`therefore r=(h)/(sqrt(n^(2)-1))`
Area `=pir^(2)`
`therefore A=(pi h^(2))/(n^(2)-1)`