Question

find the area of traiangle whose two sides are 18cm and 10cm and the perimeter is 42 cm

Answer 1

we know that,
perimeter of a triangle = sum of all sides
so,
let the unknown side be x
so,
18+10+x=42
28+x=42
x=42-28
x=14
so,
the third side =14cm

Answer 2

area of tringle is 1/2 base * height 

first tell me base ? and height ? then apply formula