One side of the rectangle is 20 cm and the diagonal is 29 find the area.

It is known from the condition that one side of the rectangle is 20 cm, and the diagonal is 29 cm. In order to find the area of the rectangle, we must know the lengths of the sides of the rectangle.

To do this, consider a right-angled triangle formed by the sides of the rectangle (legs) and the diagonal (hypotenuse).

We can find the unknown leg using the Pythagorean theorem.

The square of the hypotenuse is equal to the sum of the squares of the legs:

a ^ 2 + b ^ 2 = c ^ 2;

20 ^ 2 + x ^ 2 = 29 ^ 2;

400 + x ^ 2 = 841;

x ^ 2 = 841 – 400;

x ^ 2 = 441;

x = 21 cm second side of the rectangle.

S = a * b = 21 * 20 = 420 cm2.