RD Sharma Class 9 Solutions Chapter 15 - Areas of Parallelograms and Triangles (Ex 15.1) Exercise 15.1

We know that a plane figure bounded by four sides is called a quadrilateral. A parallelogram is a quadrilateral, where both the pairs of opposite sides are equal. In a parallelogram, the diagonals bisect each other. 

A triangle is a polygon with three sides. It also has three vertices and three edges. Furthermore, a triangle can be classified into three categories: Equilateral triangle, Isosceles triangle and Scalene triangle. 

A triangle in which all three sides are of the same length is called the Equilateral Triangle. A triangle in which any two sides are of equal length and the third side is unequal is called the Isosceles Triangle. A triangle in which all three sides are of unequal length is called the Scalene Triangle.

In the RD Sharma Book, there are three exercises in this chapter.

Some Important Formulas of the Chapter

Area of an equilateral triangle: √3/4 a², where a is the side of the equilateral triangle.

Area of an isosceles triangle: ½* b*h, where b and h denote the base and height of the isosceles triangle, respectively. 

Area of a scalene triangle:

Case 1: When the base and the height of the triangle is given. 

The area: ½* b*h (where b and h indicates the base and the corresponding height of the given triangle)

Case 2: When the length of the three sides is given. 

The area: √s(s-a)(s-b)(s-c), where a,b and c are the length of the sides of the scalene triangle, and s is the semi perimeter of the triangle.

s= (a+b+c)/2

In This Chapter, Students Will Learn Some Important Concepts From the RD Sharma Book:

1. Introduction on the areas of parallelograms and triangles

2. Different figures, using the same base, heights and parallel sides. 

3. Geometric figures.

4. Axioms and theorems on the area.

Key Benefits of Studying the RD Sharma Book:

1. RD Sharma is a self-sufficient book. It contains all the concepts explained, short notes and lots of solved and unsolved questions. This helps the students to obtain mental strength and confidence to solve complex problems.

2. The solved questions help students to have a thorough grasp of the Mathematical concepts. It also helps students in memorising and retrieving them quickly. 

3. Every question is solved and explained in a step by step, detailed method so that students do not face any difficulty while solving the problems. 

4. The answer keys boost the students’ confidence to grasp the method of solving effortlessly.

5. This book is the best study resource to gain excellence in the subject and get good marks in the examinations.