Advanced Mathematics Primary 6 Circles

A rectangle is 28 cm long and 14 cm wide. Two identical quarter circles, each of radius 14 cm, are removed from the rectangle — one at the bottom-left corner and one at the bottom-right corner, so that each quarter circle uses one full short side as a radius. Find the area of the remaining (shaded) figure. (Take π = 22/7.)

A 84 cm²
B 168 cm²
C 308 cm²
D 238 cm²
Show Worked Solution

Worked Solution

Step 1: Area of the rectangle = 28 × 14 = 392 cm². Step 2: Area of one quarter circle of radius 14 cm = (1/4) × π × r² = (1/4) × (22/7) × 14 × 14 = (1/4) × 616 = 154 cm². Step 3: Two quarter circles = 2 × 154 = 308 cm². Step 4: Remaining area = 392 − 308 = 84 cm². Answer: 84 cm²

Correct answer: 84 cm²

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