Page 210 - Math Genius C5

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\ 08-Oct-2025 Bharat Arora Proof-9 Reader’s Sign _______________________ Date __________

Step 1: Draw a rectangle around the triangles as shown.
( a) ( b)

Step 2: Divide the triangles into two parts as shown.

( a) ( b)

Step 3: Shade the rectangles with different colours and find the area of each separately.
( a) ( b)
1 2
1
2

Area of part 1 = Area of yellow square Area of part 1 = Area of yellow rectangle
= 5 × 5 = 25 sq. units = 6 × 3 = 18 sq. units

Area of yellow triangle = 25 sq. units 18
2 Area of yellow triangle = = 9 sq. units
Area of part 2 = Area of pink square 2
= 25 sq. units Area of part 2 = Area of green rectangle

Area of pink triangle = 25 sq. units = 8 × 6 = 48 sq. units
2 48
So, area of the given triangle Area of green triangle = 2 = 24 sq. units
= Area of yellow triangle + Area of pink So, area of the given triangle

triangle = 25 + 25 = 25 sq. units.
2 2 = 9 + 24 = 33 sq. units.

Example: In the adjacent figure, find the area of triangle PQR. P
Solution: Area of rectangle A = 3 × 5 sq. units
A B
= 15 sq. units

Area of rectangle B = 3 × 5 sq. units
= 15 sq. units Q R

15 15 1 1
So, area of triangle PQR = + = 7 + 7 = 15 sq. units.
2 2 2 2

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