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Example 5: Students of a school staged a rally for cleanliness campaign. They walked through the lanes in two groups. One group walked through the lanes AB, BC and CA; while the other through AC, CD and DA (see Fig. 12.12). Then they cleaned the area enclosed within their lanes. If AB = 9 m, BC = 40 m, CD = 15 m, DA = 28 m and ∠ B = 90º, which group cleaned more area and by how much? Find the total area cleaned by the students (neglecting the width of the lanes).
Prerequisite
For every question of this chapter, it will be good to learn about the derivation of Heron’s formula (also known as Hero’s formula). This tutorial is about the derivation of this formula from the other formula of the area of triangle = 1/2 * base * height. It is not a mandatory to learn this derivation to solve the questions based on this formula but is a good to know concept in case you are interested in concepts of mathematics.
Heron’s Formula
Chapter 12 – Heron’s Formula
