Mathematical Reasoning第 45 / 120 题
A circle has a radius of 6 cm. What is its circumference? (Use π ≈ 3.14.)
a.37.68 cm
b.18.84 cm
c.113.04 cm
d.12 cm
解析
Circumference equals 2πr: 2 × 3.14 × 6 = 37.68 cm. The radius is the distance from center to edge. Using the area formula πr² would instead give about 113 cm².
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