RS Aggarwal Solutions for Class 9 Chapter 11 “Areas-of-parallelograms-and-triangles”, if a triangle and a parallelogram are on the common base and between the same parallels. Then the area of the triangle is equal to half the area of the parallelogram. Area of a parallelogram, A=b×h, where b is the base of the parallelogram and h is the height of the parallelogram. Triangles: A two-dimensional flat-shaped closed figure made up of three sides and three angles is termed as triangles. The parallelograms are majorly used in industries to transfer mechanical motion from one place to another. The area of a triangle is used in finding the height of objects like bridge etc.