Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42cm.
Two sides of the triangle are 18cm and 10cm (Given)
Parameter of the triangle = 42 cm
Third side of triangle = 42 – (18 + 10)
= 14cm
Semi perimeter of triangle(s) = 
= 21cm
Using Heron’s formula,
Area of the triangle = 
= 
= 
= 
= 
cm2
30