Question

an iosocles has perimeter 30 and each the equal sides 12 find the area of the triangle

Answer 1

Length of the equal sides = 12cm
Perimeter of the triangle = 30cm
Length of the third side = 30 - (12+12) cm = 6cm
Semi perimeter of the triangle(s) = 30/2 cm = 15cm
Using heron's formula,
Area of the triangle = √s (s-a) (s-b) (s-c)
                                       = √15(15 - 12) (15 - 12) (15 - 6)cm2
                                       = √15 × 3 × 3 × 9 cm2
                                       = 9√15 cm2