1. Finding the Area of Irregular Figures
TeacherTwins©2015

2. Warm Up
Find the area.
17in 2. 1.
15in
15in
20in
17in
277.5in2
255in2

3. Ex. 1: Find the area of the irregular figure by dividing it up into rectangles and triangles.
Area of triangle = (12cm)(5cm) ÷ 2 =30 cm2
5cm
Area of rectangle = (12cm)(15cm) = 180cm2
12cm
20cm
15cm
Area = 30cm cm2
Area = 210cm2
12cm
12cm

4. Ex. 2: Find the area of the irregular figure.
20cm
3cm
17cm
5cm
15cm 1 2 3
25cm

5. Area of triangle 1
A = (15cm)(3cm) ÷ 2 =22.5cm2
Area of rectangle 2
A = (17cm)(15cm) = 255cm2
Area of triangle 3
A = (15cm)(5cm) ÷ 2 = 37.5 cm2
Area = 22.5cm cm cm2 = 315cm2

6. Practice Find the area. 57.5cm2 170cm2 7cm 2cm 20cm 5cm 14cm 2cm 12cm

7. Closure
Explain how to find the area of an irregular figure.