Question

triangle has sides 200,172 and155
find area

Answer 1

I would find the angle Ø across from the 155 side by
155^2 = 200^2 + 172^2 - 2(200)(172)cosØ

then area of triangle
= (1/2)(200)(172)sinØ

or

you might want to "google" Heron's formula

for any triangle with sides a, b , and c
let s = (1/2)(a+b+c)

then the area of the triangle
= √(s(s-a)(s-b)(s-c))