The perimeter of a rectangle is 80 cm. Find the lengths of the sides of the rectangle

The lengths of the sides are 20 cm and 20 cm

Step-by-step explanation:

Given

Perimeter, P = 80cm

Represent the length and width with L and W, respectively;

Substitute 80 for P

Divide through by 2

Make L the subject of formula

Area of a rectangle is calculated as thus;

Substitute 40 - B for L

Express this as a function

Set A(B) = 0 to determine the roots

Hence;

or

or

or

The maximum area of a rectangle occurs at half the sum of the roots;

So;

Recall that

Hence the lengths of the sides are 20 cm and 20 cm