Chapter 9 Class 9 Areas of Parallelograms and Triangles

Get NCERT Solutions of Chapter 9 Class 9 Areas of Parallelograms and Triangles free at teachoo. All questions have been solved with video of each and every exercise question and example.

 

Theorems 9.1, 9.2, 9.3 have also been explained with proofs and videos.

 

We have Studied formulas of Area of Parallelogram and Triangle before.

Area of Parallelogram = Base × Height

Area of Triangle = 1/2 × Base × Height

 

In this chapter, we use Theorems to provide Area of figures equal.

Let's see what we will learn in the chapter:

  • If two figures are congruent, then they have the same area. But opposite may not be true.
  • We can divide a figure into parts, Area of figure will be sum of the parts
  • Figures with same base, and between same parallel lines
  • Theorem 9.1 - Parallelogram with the same base, and between the same parallel lines are equal in area
  • If triangle and parallelogram have the same base, and are between same parallel lines. Then, Area of triangle is 1/2 of Area of parallelogram (Proof is in Example 2)
  • Theorem 9.2 - If two triangles have the same base, and are between same parallel lines, their area will be equal
  • And converse of Theorem 9.2, Theorem 9.3 - If two triangles have same base, and are equal in area. Then, they must lie between same parallels
  • And median of a triangle divides it into two triangles of equal areas (Proof is in Example 3)

 

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