Question 37
Mensuration of Plane ShapesIn the figure above, PQRS is a rectangle. If the shaded area is 72sq.cm, find h.
- A.12cm
- B.10cm
- C.8cm
- D.5cm
Show the answer and explanation
Answer: D (5cm)
Explanation
The rectangle is 2h by 3h and the unshaded part inside is (2h − 4) by (3h − 2). Shaded area = 6h² − (2h − 4)(3h − 2) = 16h − 8 = 72, so h = 5cm.