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Circumference, Area,
Surface Area, and Volume
By Taylor Winter
Derive the Formula:
Area of a Trapezoid
Example Problems
1. A trapezoid has a base 1 of 4 cm and a base 2 of 6 cm. The height is 5 cm. What is the area?
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Area of a trapezoid= (b1+b2) x h/ 2
b1= 4 cm b2= 6 cm h= 5 cm
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(4 cm + 6 cm) x 5 cm/ 2
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(10 cm) x 5 cm/ 2
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50 cm^2/ 2
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The area of the trapezoid is 25 cm^2.
Create a congruent trapezoid then using the moving and additive principle use the two congruent triangles to create a parallelogram.
The new parallelogram has an area two times the area of the original trapezoid.
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We know that the area of a parallelogram is base x height.
The base of the parallelogram is base 1 + base 2 of the trapezoid.
The height is the same as the original trapezoid.
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Area of a trapezoid is (base 1 + base 2) x height divided by 2.
2. A trapezoid has a base 1 of 5 cm and a base 2 of 10 cm. The height is 4 cm. What is the area of the trapezoid?
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Area of a trapezoid= (b1 + b2) x h/ 2
b1= 5 cm b2= 10 cm h= 4 cm
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(5 cm + 10 cm) x 4 cm/ 2
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15 cm x 4 cm/2
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60 cm^2/2
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The area of the trapezoid is 60 cm^2.
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