Question

find the area of triangle two sids are 18cm and10cm and perimeter is 42cm

Answer 1

If two sides are 18cm and 10cm
and its perimeter=42
Then Perimeter= Sum of three sides
Let third side be x
42=18+10+x
42=28+x
x=42-28
×=14
And its semi perimeter be 21
So use Herons formulla to find area of a triangle

Answer 2

third side of a triangle is equal to = 42-28
= 14 cm
area according to heron's formula
area = √s(s-a)(s-b)(s-c)
√21(3)(11)(7)
= 7×3√11
= 21√11 cm² ans.