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AREA OF TRIANGLE
MathsPrimary 5 By: Jinky Dabon
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Get a rectangular piece of paper and cut it diagonally as shown below.
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You will obtain two triangles with each triangle having half the area of the triangles.
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The formula for calculating the area of a triangle is:
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Area of ∆ = ½ x base x height
Area of Triangle
= ½ x area of rectangle
= ½ x length x width (of rectangle)
= ½ x length x width (of rectangle)
= ½ x base x height (of triangle)
Length (Base)
Width
(Height)
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Calculate the area of ∆ RST.
R
Answer: The area of ∆ RST is 42 square centimetres or 42 cm².
Area of ∆ RST
= ½ x base x height
14 cm
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T
6 cm
= ½ x 6 cm x 14 cm
= 42 square centimetres or 42 cm²
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Calculate the area of ∆ LMN.
M
Answer: The area of ∆LMN is 28 square centimetres or 28 cm².
Area of ∆ LMN
= ½ x base x height 8 cm
N
L
7 cm
= ½ x 7 cm x 8 cm
= 28 square centimetres or 28 cm²
O
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Calculate the area of the triangle.
Area = _____ square metres or ______ m².
15 m
9 m
67.5 67.5
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Calculate the area of the triangle.
Area = ___ square centimetres or _____ cm².
18 cm
15 cm
135 135
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Calculate the area of the triangle.
Area = _____ square metres or ______ m².
28 m
17 m
238 238
