1. Finding the Area of Special Quadrilaterals
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2. Warm Up
1. Find the area of a rectangle with a width of 11.5in and a length of 15.4in.
2. Find the area of a parallelogram with a base of 12cm and a height of 18cm.
3. Find the area of a triangle that has a base of 22ft and a height of 18ft.
4. Find the area of a right triangle that has a base of 14ft and a height of 17ft.
177.1in2
216cm2
198ft2
119ft2

3. Finding the Area of a Rhombus
A rhombus is a parallelogram so we can use the formula A = base x height.

4. Ex. 1: Find the area of the rhombus.
A = (15cm)(10cm)
A = 150cm2
Height - 10cm
15cm - base

5. Finding the Area of Trapezoid

6. Example 2: Find the area of the trapezoid.
To find the base of the triangle subtract the bases.
15cm – 7cm = 8cm.
7cm
Divide the 8cm by 2 to find out the base of one of the triangles. 8/2 = 4cm
5cm
4cm
4cm
15cm
Find the area of the rectangle.
A = 7cm x 5cm = 35cm2
Find the area of the triangles.
A = 4(5)÷ 2 = 10 cm2
Add the two triangles and the rectangles.
10cm2 + 10cm2 + 35cm2 = 55cm2

7. Example 3: Find the area. A = 17.5in2 + 17.5in2 + 84in2 = 119in2
Base of triangles = 22in – 12in = 10in
10 ÷ 2 = 5in
12in
Area of triangles
A = 5in x 7in ÷ 2 = 17.5in2
7in
5in
5in
Area of rectangle
A = 12in x 7in = 84in2
22in
Add the rectangle and two triangles.
A = 17.5in in in2 = 119in2

8. Practice
Find the area. 1.
16cm 2.
12cm
12cm
20cm
14cm
216cm2
168cm2

9. Closure
Explain how to find the area of the trapezoid to a student who was not here.
7cm
5cm
10cm
42.5cm2