## There is a slide in the park.

[question] Question. There is a slide in the park. One of its side walls has been painted in the same colour with a message “KEEP THE PARK GREEN AND CLEAN” (see the given figure). If the sides of the wall are 15m, 11m, and 6m, find the area painted in colour. [/question] [solution] Solution: t can be observed that the area to be painted in colour is a triangle, having its sides as 11 m, 6 m, and 15 m. Perimeter of such a triangle $=(11+6+15) \mathrm{m}$ $2 s=32 \mathrm{~m}$ $s=16 \mathrm{~m}$ By...

## A traffic signal board, indicating ‘SCHOOL AHEAD’

[question] Question. A traffic signal board, indicating ‘SCHOOL AHEAD’, is an equilateral triangle with side ‘a’. Find the area of the signal board, using Heron’s formula. If its perimeter is 180 cm, what will be the area of the signal board? [/question] [solution] Solution: Side of traffic signal board = a Perimeter of traffic signal board $=3 \times a$ $2 s=3 a \Rightarrow s=\frac{3}{2} a$ By Heron’s formula, Area of triangle $=\sqrt{s(s-a)(s-b)(s-c)}$ Area of given triangle \$=\sqrt{\frac{3}{2...