Question
An umbrella is made by stitching 10 triangular pieces of cloth of two different colours (see figure), each piece measuring 20 cm, 50 cm and 50 cm: How much cloth of each colour is required for the umbrella?

Solution
For one triangular piece
a = 20 cm b = 50 cm c = 50 cm
Area of one triangle
∴ Area of five triangles of one colour
Hence, 1000 cm2 of each colour is required for the umbrella.