Standard Mathematics Primary 6 Circles

The area of a circular coaster is 78.5 cm². What is the radius of the coaster? (Use π = 3.14)

A 5 cm
B 10 cm
C 12.5 cm
D 25 cm
Show Worked Solution

Worked Solution

Step 1: Write the area formula: A = πr². Step 2: Substitute A = 78.5 and π = 3.14: 78.5 = 3.14 × r². Step 3: Solve for r²: r² = 78.5 ÷ 3.14 = 25. Step 4: Find r: r = √25 = 5 cm. The radius of the coaster is 5 cm. Answer: 5 cm

Correct answer: 5 cm

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