Question

If the semi perimeter of a triangle is 21cm and two of its sides are 13cm and 15cm, then its area (in cm 2 ) is

Answer 1

Given semi perimeter of a triangle is 21 cm
If two sides of the triangle are 12 cm, 15 cm
Then it's area =?
Semi Perimeter =(a+b+c)/2
21=(13+15+c)/2
42=28+c
c=42-28
c=14

Area of triangle =square root of [s(s-a)(s-b)(s-c)]
Area =square root of [21 (21-13) (21-14)(21-15)]
Area =square root of [21×8×7×6]
Area =square root of [3×7×4×2×7×3×2]
Area =3×7×2×2
Area =21×4
Area =84 square cm