Question

find the area of isosceles triangle whose equal sides is 8 cm and the base is 9 cm

Answer 1

Semi-perimeter = a + b + c / 2
                         = 8 + 8 + 9/2
                         = 25/2
                         = 12.5 

Area of triangle = √ s (s-a) (s-b) (s-c)
                         = √ 12.5 (12.5 - 8) (12.5-8) (12.5-9)
                         = √ 12.5 x 4.5 x 4.5 x 3.5
                         = √ 885.9375
                         =  29.77

So, 29.77 is the area of triangle.
      
                  

Answer 2

The area of the triangle can be found using Heron's Formula.
a = 8cm, b =8cm, c= 9cm

Semi perimeter = a +b+c/2 = 8+8+9 /2= 25/2
= 12.5cm

Now area = √s(s -a)(s - b)(s -c)
= √12.5(12.5 - 8)(12.5 - 8)(12.5 - 9)
= √12.5 x 4.5 x 4.5 x 3.5
= √885.9375
= 29.77 cm^2