One side of the triangle is 7cm, the other 8cm. and the third is 4 cm larger than the second side. Find the perimeter of the triangle.

The first side of the triangle is a = 7 cm.
The second side of the triangle is b = 8 cm.
The third side of the triangle c = b + 4 cm = 8 + 4 = 12 cm.
As you know, the perimeter of a triangle is the sum of all sides, and is calculated using the following formula: P = a + b + c.
Substitute all the known values of the sides of the triangle in the formula and find the perimeter: P = 7 + 8 + 12 = 27 cm.
Answer: the perimeter of a triangle given by the lengths of its sides is 27 cm.