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Last updated at Dec. 8, 2016 by Teachoo

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

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.