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Chapter 12 Class 9 Herons Formula
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Ex 12.1, 6 - An isosceles triangle has perimeter 30 cm - Ex 12.1

Ex 12.1, 6 - Chapter 12 Class 9 Herons Formula - Part 2
Ex 12.1, 6 - Chapter 12 Class 9 Herons Formula - Part 3

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Ex 12.1, 6 An isosceles triangle has perimeter 30 cm and each of the equal sides is 12 cm. Find the area of the triangle. 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 triangle is isosceles In isosceles triangle, two sides are equal So, a = b = 12 cm and Perimeter = 30 cm Semi-Perimeter = s =Perimeter/2 s = 30/2 s = 15 cm We need to find c Perimeter = 30cm a + b + c = 30 cm 12 cm+ 12 cm + c = 30 cm 24 + c = 30 c = 30 24 c = 6 cm Area of triangle = ( ( )( )( )) Putting a = 12 cm, b =12 cm, c = 6 cm & s = 15 cm = (15(15 12)(15 12)(15 6)) = (15(3)(3)(9)) = (15 (9)(9)) = ("9" 9) 15 = ("92" ) 15 = (9) 15 = 9 15 Thus, Area = 9 15 cm2

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.