Question

Mrs. Harper asked the class to find the area of an isosceles trapezoid.

Suzy decomposed the trapezoid and rearranged the parts to form

a rectangle of equal area as shown.
Which pair of expressions represents the area

of the trapezoid and rectangle?




12(5 X 4) and (8 – 3)(4)




12(2 + 8)(4) and (2 + 3)(4)




8 X 5 and 2(5)(4)




2(8 + 4) and (8 – 2)(4)

Answer 1

Area of trapezoid:-

• 1/2(Sum of parallel sides)(Height)

Put the values

• 1/2(2+8)(4)
• 2(10)
• 20units²

Answer 2

1/2(2 + 8)(4) and (2 + 3)(4)

area of trapezoid:

`\sf (1)/(2) (a + b) *h`

Here:

• height: 4 unit
• a, side 1: 2 unit
• b, side: 8 unit
• slant height: 5 unit

So area of this trapezium:

`\sf (1)/(2) (2 + 8) *4`

`\sf 20 \ units`

area of rectangle:

length * width

5 * 4

20 units²