Find the area of the shaded region.

[1]
A1 = (h (a + b)) / 2
A1 = (21 (17 + 32)) / 2
A1 = (21 x 49) / 2
A1 = 1,029 / 2
A1 = 514.5 mm²
[2]
A2 = (b x h) / 2
A2 = (11 x 9) / 2
A2 = 99 / 2
A2 = 49.5 mm²
[3]
The area of the shaded region =
A1 - A2 =
514.5 mm² - 49.5 mm² =
465 mm²
The answer is 465 mm².