Answer:
A: Find the area of the outer trapezoid and then subtract the area of the inner trapezoid
B: 15 square units
Step-by-step explanation:
A:
Find the area of the outer trapezoid and then subtract the area of the inner trapezoid
(because if the inner trapezoid wasn't there and you were looking for the shaded region, you'd find the area of the outer trapezoid. since you have to take away the area the inner trapezoid takes up, the shaded region = area of outer trapezoid - area of inner trapezoid)
B
The area of a trapezoid is ((a+b)/2)h, where a is the top or the trapezoid, b is the bottom and h is the height.
The top of the outer trapezoid ranges from 4 to 6, so a=6-4=2. The bottom of the outer trapezoid ranges from 2 to 8, so b=8-2=6. The height of the outer trapezoid ranges from 2 to 8, so h=8-2=6.
The area of the outer trapezoid = ((a+b)/2)h = ((2+6)/2)(6) = 4(6) = 24
The top of the inner trapezoid ranges from 4 to 6, so a=6-4=2. The bottom of the inner trapezoid ranges from 3 to 7, so b=7-3=4. The height of the inner trapezoid ranges from 3 to 6, so h=6-3=3.
The area of the inner trapezoid = ((a+b)/2)h = ((2+4)/2)(3) = 3(3) = 9
The are of the shaded region = the area of the outer trapezoid - the area of the inner trapezoid = 24 - 9 = 15 square units
