Question

Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42cm?​

Answer 1

let, a=18cm,b=10cm,s=42/2=21cm

in a triangle,

a+b+c=perimeter

18+10+c=42cm

28+c=42

c=42-28=14cm

area of a triangle=√s(s-a)(s-b)(s-c)=√21(21-18)(21-10)(21-14)

=√21×3×11×7=√4851=7√99cm²

I hope that u will completely understand it...