Question

what is the area, in square meters, of the shaded part of the rectangle below?
9 m
20 m
4 m

Explanation:

Step1: Find area of rectangle

The formula for the area of a rectangle is \( A = l \times w \), where \( l = 20 \, \text{m} \) and \( w = 9 \, \text{m} \). So, \( A_{\text{rectangle}} = 20 \times 9 = 180 \, \text{m}^2 \).

Step2: Find area of unshaded triangle

The base of the triangle is \( 20 \, \text{m} \), and the height is \( 9 - 4 = 5 \, \text{m} \). The formula for the area of a triangle is \( A = \frac{1}{2} \times b \times h \). So, \( A_{\text{triangle}} = \frac{1}{2} \times 20 \times 5 = 50 \, \text{m}^2 \).

Step3: Subtract triangle area from rectangle area

To find the area of the shaded part, subtract the area of the unshaded triangle from the area of the rectangle: \( A_{\text{shaded}} = 180 - 50 = 130 \, \text{m}^2 \).

Answer:

130