show that of all the rectangles in a given fixed circle,the square has the maximum area.

Hi Anushka

Here in  h = r sin θ , 

The area of a rectangle ie. length * breadth or

{BD X (AO +CO)}  ie {2r X (h+h)}

by dividing rectangle in two half triangles and calculating each. (half X base X Height) X 2

will be maximum when h will be max. and h is maximum only when θ = 90.

which makes rectangle a square