The rectangle is inscribed in a right angled triangle.
\ and
are the side of the rectangle.
The sides of the triangle are and
.
Two points form of a line equation is .
The two points are and
is
The area of the rectangle is .
The area of the rectangle is maximum when its first derivative becomes zero.
\Apply derivative on each side with respect to .
\
Equate to zero.
The length of the rectangle is .
Substitute in
.
Therefore the area of the largest rectangle that is inscribed in a right angled triangle is .
\ \
The area of the largest rectangle that is inscribed in a right angled triangle is .