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

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.

Hi, it looks like you're using AdBlock :(

Displaying ads are our only source of revenue. To help Teachoo create more content, and view the ad-free version of Teachooo... please purchase Teachoo Black subscription.

Please login to view more pages. It's free :)

Teachoo gives you a better experience when you're logged in. Please login :)

Solve all your doubts with Teachoo Black!

Teachoo answers all your questions if you are a Black user!