Mathematics for IGCSE & O level - Estimation (Section 2 - No. 12)
When calculating the area of a circle, the radius is measured as 5.3 cm. Estimate the area of the circle by rounding the radius to 1 significant figure.
78 cm²
90 cm²
80 cm²
70 cm²
Explanation
Round 5.3cm to 5cm, apply the area of a circle formula πr² which would be π x 5² = 78.5 cm² . Therefore 80 cm² is the estimation.
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