Question 1
A regular hexagon is divided into 6 congruent triangular sections. If each triangular section has an area of 15.6 square centimeters, and a circular hole with radius 2 cm is cut from the center of the hexagon, what is the area of the remaining figure? (Use π ≈ 3.14)
- 81.04 cm² (correct answer)
- 85.04 cm²
- 89.04 cm²
- 93.04 cm²
Explanation: The total area of the hexagon is 6 × 15.6 = 93.6 cm². The area of the circular hole is πr² = 3.14 × 2² = 3.14 × 4 = 12.56 cm². The remaining area is 93.6 - 12.56 = 81.04 cm². Choice B (85.04) might result from using radius 1.5 cm for the hole. Choice C (89.04) might result from using a hole area of 4.56 cm². Choice D (93.04) might result from using a hole area of only 0.56 cm².
Question 2
A trapezoid has parallel bases of lengths 14 meters and 8 meters. If the area of the trapezoid is 132 square meters, and a rectangular section with width equal to the shorter base is removed from the center, what is the area of the remaining figure when the height of the removed rectangle is 3 meters?
- 108 square meters (correct answer)
- 114 square meters
- 120 square meters
- 126 square meters
Explanation: First, find the height of the trapezoid using the area formula: Area = (1/2)(b₁ + b₂)h, so 132 = (1/2)(14 + 8)h = (1/2)(22)h = 11h. Therefore h = 12 meters. The removed rectangle has width 8 meters (shorter base) and height 3 meters, so its area = 8 × 3 = 24 square meters. The remaining area = 132 - 24 = 108 square meters. Choice B (114) might result from using height 2 for the rectangle. Choice C (120) might result from removing a 3×4 rectangle. Choice D (126) might result from removing only a 2×3 rectangle.
Question 3
A parallelogram has a base of 16 inches and a height of 9 inches. Three congruent triangular pieces, each with area 18 square inches, are cut out from the parallelogram. What percentage of the original parallelogram area remains?
- 52.5%
- 62.5% (correct answer)
- 67.5%
- 72.5%
Explanation: The area of the parallelogram is base × height = 16 × 9 = 144 square inches. Three triangular pieces with area 18 square inches each are removed, so total removed area = 3 × 18 = 54 square inches. Remaining area = 144 - 54 = 90 square inches. Percentage remaining = (90/144) × 100% = 62.5%. Choice A (52.5%) results from removing 68 sq in instead of 54. Choice C (67.5%) results from removing 47 sq in. Choice D (72.5%) results from removing 40 sq in.
Question 4
A rhombus has diagonals of length 18 cm and 24 cm. If two identical right triangles are removed from opposite corners, each with legs of length 3 cm and 4 cm, what is the area of the remaining figure?
- 198 cm²
- 204 cm² (correct answer)
- 210 cm²
- 216 cm²
Explanation: The area of a rhombus is (1/2) × d₁ × d₂ = (1/2) × 18 × 24 = 216 cm². Each right triangle has area (1/2) × 3 × 4 = 6 cm². Since two triangles are removed, total removed area = 2 × 6 = 12 cm². Remaining area = 216 - 12 = 204 cm². Choice A (198) results from removing 18 cm² instead of 12. Choice C (210) results from removing only 6 cm². Choice D (216) results from not removing any area.