Answer:
c) 18 cm²
d) 30 cm²
Explanation:
c)
You can do this 2 different ways. Either way, you need to use the bottom side of 8 cm and the two congruent segments. Each of the two congruent segments of the bottom side measures 4 cm.
Method 1) Find the area of the large triangle and subtract from it the area of the small triangle.
area of triangle = bh/2
shaded area = 8 cm × 6 cm / 2 - 4 cm × 3 cm / 2
shaded area = 24 cm² - 6 cm²
shaded area = 18 cm²
Method 2) The shaded region is a trapezoid with parallel bases of lengths 3 cm and 6 cm and height 4 cm. Find the area of the trapezoid.
area of trapezoid = (B + b)h/2
shaded area = (6 cm + 3 cm)(4 cm)/2
shaded area = (9 cm)(4 cm)/2
shaded area = 18 cm²
d)
The area of the shaded region is the area of the white triangle subtracted from the area of the rectangle.
area of rectangle = length × width
area of triangle = bh/2
shaded area = (12 cm)(4 cm) - (9 cm)(4 cm)/2
shaded area = 48 cm² - 18 cm²
shaded area = 30 cm²