web analytics

Ex 12.1, 3 - There is a slide in the park. One of its side - Finding area of triangle

  1. Chapter 12 Class 9 Herons Formula
  2. Serial order wise
Ask Download

Transcript

Ex 12.1, 3 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 green colour. Area of triangle = √(s(s−a)(s−b)(s −c)) Here, s is the semi-perimeter, and a, b, c are the sides of the triangle Given sides of triangle 15 m, 6m , 11 m So, a = 15 m, b = 6m , c = 11 m s = (𝑎 + 𝑏 + 𝑐)/2 Area of triangle = √(𝑠(𝑠 −𝑎)(𝑠 −𝑏)(𝑠 −𝑐)) Putting a = 15 m, b = 6m , c = 11 m , s = 16 m =√(16(16−11)(16−6)(16−15)) m2 = √(16×5×10×1) m2 = √16×√(5×10) m2 = √16×√(5×5×2) m2 = √16×√(5×5) " "×√2 m2 = √42×√52 " "×√2 m2 = 4 × 5 ×√2 m2 = 20 √2 m2 Therefore, the area painted in colour is = 20 √2 m2 .

About the Author

CA Maninder Singh's photo - Expert in Practical Accounts, Taxation and Efiling
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 8 years. He provides courses for Practical Accounts, Taxation and Efiling at teachoo.com .
Jail