One side of the rectangle is 21 cm, the other is 8 cm larger than the first, to know the perimeter and area of the rectangle.

First of all, we calculate the unknown side of the rectangle if it is 8 cm larger than the other. which by condition is equal to 21 cm:

21 + 8 = 29 (cm).

We now calculate the perimeter of a rectangle with sides of 21 cm and 29 cm, which is equal to the doubled sum of its two sides:

P = 2 (21 + 29) = 2 * 50 = 100 (cm).

Find the area of a rectangle with sides 21 cm and 29 cm by multiplying the lengths of the sides by each other:

S = 21 * 29 = 609 (cm²).

Answer: the perimeter of the rectangle is 100 cm, the area of the rectangle is 609 cm².