Area of rectangle with perimeter 25 and side 5 equal to 37.5
where a and b are sides.
A rectangle is a geometric shape that has four right angles (90°) and opposite sides are equal and parallel.
Rectangle area formula 
or 
where a or b - side, P is the perimeter.
or 
where d is diagonal, a or b - side.
where d is diagonal, α° is the angle between them in degrees.
or 
where R is the radius of the circumscribed circle, a or b - side.
or 
where R is the radius of the circumscribed circle, a or b - side.Solution:
S =
P·a - 2·a2
2
=
25·5 - 2·52
2
=
125 - 50
2
=
75
2
=
37.5
a: Area of rectangle with perimeter 25 and side 5 equal to 37.5