There is a slide in a park. One of its side walls has been painted in some colour with a message “KEEP THE PARK GREEN AND CLEAN” (see Fig. 12.10 ). If the sides of the wall are 15 m, 11 m and 6 m, find the area painted in colour.
Solution
Sides of the triangular wall are 15 m, 11 m and 6 m.
Semi perimeter of triangular wall (s) = (15 + 11 + 6)/2 m = 16 m
Using heron's formula,
Area of the message = √s (s-a) (s-b) (s-c)
= √16(16 - 15) (16 - 11) (16 - 6) m2
= √16 × 1 × 5 × 10 m2 = √800 m2
= 20√2 m2
