The sides of a triangle are 8 cm, 11 cm and 13 cm. What is its area?

The area of a triangle can be calculated using Heron's formula when the lengths of all three sides are known. Heron's formula is given by:

Area = sqrt[s(s - a)(s - b)(s - c)]

where a, b, and c are the sides of the triangle, and s is the semi-perimeter of the triangle. The semi-perimeter is calculated as:

s = (a + b + c) / 2

Given that the sides of the triangle are 8 cm, 11 cm, and 13 cm, we can calculate s as:

s = (8 + 11 + 13) / 2 = 16 cm

Substituting s, a, b, and c into Heron's formula gives:

Area = sqrt[16(16 - 8)(16 - 11)(16 - 13)] = sqrt[16 * 8 * 5 * 3] = sqrt[19200] = 138.56 cm^2

So, the area of the triangle is approximately 138.56 cm^2.