Question

an isosceles triangle has perimeter 30 centimetre and each of equal side is 12 centimetre.

find the area of triangle

Answer 1

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Answer 2

Perimeter of triangle = 30 cm
two sides = 12 cm and 12 cm each (equal side)
3rd side = 30 - (12+12) = 30 - 24 = 6

we'll find area by heron's formula.

semi perimeter = perimeter/2 = 30/2 = 15 = s

area of the triangle = √s(s-a)(s-b)(s-c)       
( where a, b and c are sides of triangle)
                            = √15(15-12)(15-12)(15-6)
                            = √15 x 3 x 3 x 9
                            = 9√15

so, area of triangle = 9√15cm²