23
Oct
Example 2: A triangular park ABC has sides 120m, 80m and 50m (see Fig. 12.7). A gardener Dhania has to put a fence all around it and also plant grass inside. How much area does she need to plant? Find the cost of fencing it with barbed wire at the rate of Rs. 20 per metre leaving a space 3m wide for a gate on one side.
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
