Jasper Eng's answer to Felice's Primary 6 Maths Geometry Singapore question.
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Consider the NON- overlapping region:
The shaded area is the SAME
As the trapezium at the bottom portion:
17.14cm - 6cm = 11.14cm
Area of trapezium
= 1/2 * (sum of parallel length) * height
= 1/2 * (11.14 + 17.14) * 12.5
= 176.75cm^2
:. Area of shaded region
= Area of Trapezium
= 176.75cm^2
The shaded area is the SAME
As the trapezium at the bottom portion:
17.14cm - 6cm = 11.14cm
Area of trapezium
= 1/2 * (sum of parallel length) * height
= 1/2 * (11.14 + 17.14) * 12.5
= 176.75cm^2
:. Area of shaded region
= Area of Trapezium
= 176.75cm^2
Date Posted:
3 years ago
How could 12.5cm be the height of trapezium?
How did 17.14cm & 11.14cm be the sum of the parallel sides?
Sorry. I really don't understand.
How did 17.14cm & 11.14cm be the sum of the parallel sides?
Sorry. I really don't understand.
See Sstrike's diagram for the trapezium.
The trapezium (Area A) can be divided into 2 triangles , each with a height of 12.5cm
One triangle has a base of 11.4cm, the other has a base of 17.4cm
Area A
= ½ × 17.4cm × 12.5cm + ½ × 11.4cm × 12.5cm
= ½ × (17.14 + 11.14)cm × 12.5cm
= ½ × 28.28cm × 12.5cm
= 14.14cm × 12.5cm
= 176.75cm²
The trapezium (Area A) can be divided into 2 triangles , each with a height of 12.5cm
One triangle has a base of 11.4cm, the other has a base of 17.4cm
Area A
= ½ × 17.4cm × 12.5cm + ½ × 11.4cm × 12.5cm
= ½ × (17.14 + 11.14)cm × 12.5cm
= ½ × 28.28cm × 12.5cm
= 14.14cm × 12.5cm
= 176.75cm²
The area of a trapezium (which you will learn in secondary school level) is basically derived from the combined area of the two triangles that form it.
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