Question

area of isosceles triangle whose side are 12cm each and the perimeter is 30cm.

Answer 1

Let the third side of this triangle be x.Perimeter of triangle = 30 cm12 cm + 12 cm + x = 30 cmx = 6 cm
s= perimeter of the triangle /2 = 30/2 = 15cm
by Herons formula,
         area of the triangle = (root of) s(s-a)(s-b)(s-c)
                                         =  (root of) 15 x (15-12) (15-12) (15-6)
                                        = (root of) 15 x 3 x 3 x 9
                                        =  (root of) 3 x 5 x 3 x 3 x 3 x 3
                                       = 3 x 3 (root of) 5 x 3
 
                                        = 9 (root of) 15 cm^3

Answer 2

there r three sides
so, sides r =12cm,9cm,9cm
area=18root5 cm^2
by herons formula