find the dimensions of the rectangles of largest area that can be inscribed in a circle of Radius a
Here is the link for the answer to a similar query:
https://www.meritnation.com/ask-answer/question/show-that-the-rectangle-of-maximum-area-that-can-be-inscrib/application-of-derivatives/5163162
https://www.meritnation.com/ask-answer/question/show-that-the-rectangle-of-maximum-area-that-can-be-inscrib/application-of-derivatives/5163162