Maths Class 9 Chapter 9 Areas of Parallelograms and Triangles

# Maths Class 9 Chapter 9 Areas of Parallelograms and Triangles

Important Concepts and Formulas

1.      Area of a figure is the part of the plane enclosed by that figure.

2.      Two congruent figures have equal areas but the converse need not be true.

3.      If a plane region P is made up of two non-overlapping plane regions Q and R, then area of P = area of Q + area of R.

4.      Two figures are said to be on the same base and between the same parallel lines, if they have a common base (side) and the vertices opposite to the common base of each figure lie on a line parallel to the base.

5.      Parallelograms on the same base (or equal base) and between the same parallels are equal in area.

6.      The area of a parallelogram is the product of its base and the corresponding height.

7.      Parallelograms on the same base (or equal base) and having equal areas lie between the same parallels.

8.      If a parallelogram and a triangle are on the same base and between the same parallels, then the area of the triangle is half the area of the parallelogram.

9.      Triangles on the same base (or equal base) and between the same parallels are equal in area.

10. Area of a triangle is half the product of its base and the corresponding height.

11. Triangles on the same base (or equal base) and having equal areas lie between the same parallels.

12. Each median of a triangle divides it into two triangles of equal areas.

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