NCERT Class 9 Solutions: Heron's Formula (Chapter 12) Exercise 12.2 Part 2
Q3 Radha made a picture of an airplane with colored paper as shown in figure. Find the total area of the paper used.
Solution:
We can divide the airplane into the separate quadrilaterals and triangles. Let’s find each of their areas
For triangle (i)
This triangle is an isosceles triangle, therefore its perimeter and semiperimeter
By using heroes formula, area of the triangle







(approx.)
For quadrilateral (ii)
Area of Rectangle
For quadrilateral (iii)
This quadrilateral is a trapezium. To find the area we need to first find its height. =
For triangle (IV) = triangle (v)
We know


(2 triangle)

Therefore, total area of the paper used