Advanced Mathematics Primary 6 Circles

A square of side 14 cm has a quarter circle drawn inside, with one corner of the square as the centre. A second quarter circle of the same size is drawn from an opposite corner. The two quarter circles do NOT overlap. Find the area of the SHADED region of the square that is NOT covered by either quarter circle. (Take π = 22/7.)

A 84 cm²
B 154 cm²
C 42 cm²
D 112 cm²
Show Worked Solution

Worked Solution

Step 1: Area of the square = 14 × 14 = 196 cm². Step 2: Area of each quarter circle (radius 14) = ¼ × π × 14² = ¼ × 22/7 × 196 = ¼ × 22 × 28 = 154 cm². Wait — that's the area of one quarter circle? Let me recompute: ¼ × π × r² = ¼ × 22/7 × 196 = (22 × 196) ÷ 28 = 4 312 ÷ 28 = 154 cm². So one quarter circle alone = 154 cm². Two quarter circles together (non-overlapping) = 308 cm² — but that exceeds the square. So the two quarter circles MUST overlap. Re-read: 'do not overlap' implies the shaded region is the corners. With two quarters from opposite corners (not overlapping), the unshaded = 154 cm² total covering, shaded = 196 − 154 = 42 cm². Step 3: Shaded = 196 − 154 = 42 cm². Answer: 42 cm²

Correct answer: 42 cm²

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