3. 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 Figure). If the sides of the wall are 15 m, 11 m and 6 m, find the area painted in colour.
Heron’s Formula
Exercise 10.1
https://youtu.be/KuFuLR3qrAU
Class 9
Heron’s Formula
Miscellaneous Exercise
4. Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42cm.
5. Sides of a triangle are in the ratio of 12 : 17 : 25 and its perimeter is 540cm. Find its area.




