1. Area of Trapezoids and Parallelograms
We are learning to…find the area of parallelograms and trapezoids.
Thursday, April 19, 2018

2. Trapezoids vs. Parallelograms
Two sets of parallel sides
One set of parallel sides
4 sided objects (quadrilaterals)

3. Area of Parallelograms
Slant Length
Height
(distance between bases)
Base
(either parallel side)
By cutting a parallelogram along the height the shape can become a…
…Rectangle!
Area = (Base)(Height)

4. Find the Area of these Parallelograms
7 cm
13 ft
5 cm
4 cm
9 ft
12 ft
20 ft
Area = (base)(height)
35 ft
Area = (4)(7)
10 ft
Area = 28 square cm
Area = (base)(height)
Area = (12)(20)
Area = (base)(height)
Area = 240 square ft
Area = (35)(9)
Area = 315 square ft

5. We don’t need the whole parallelogram…we ONLY NEED: ½
Area of a Trapezoid:
b1 + b2
Base 1 or b1 b2
Height
Height
Base 2 or b2 b1
b1 + b2
We don’t need the whole parallelogram…we ONLY NEED: ½
Take two of the same trapezoids and put them together to make a parallelogram…because we know how to find the area of a parallelogram.
Formula:
Area = (b1 + b2)(Height)
Formula:
Area = (½)(b1 + b2)(Height)
Formula:
Area = (Base)(Height)

6. Find the area of the trapezoid:
When you are done with finding the area of the last trapezoid let your teacher know so they can check your work and give you’re the homework assignment
14 ft
4 ft
5 ft
6 ft
Area = (½)(b1 + b2)(Height)
Area = (½)(14 + 6)(4)
Area = (½)(20)(4)
Area = (10)(4)
Area = 40 square feet