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If the area of a circle is 78.5 cm², what is the radius? (2021)
If the area of a circle is 78.5 cm², what is the radius? (2021)
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If the area of a circle is 78.5 cm², what is the radius? (2021)
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Area = πr²; 78.5 = π * r²; r² = 78.5/π = 25; r = 5 cm.
Questions & Step-by-step Solutions
1 item
Q
Q: If the area of a circle is 78.5 cm², what is the radius? (2021)
Solution:
Area = πr²; 78.5 = π * r²; r² = 78.5/π = 25; r = 5 cm.
Steps: 6
Show Steps
Step 1: Write down the formula for the area of a circle, which is Area = πr².
Step 2: Substitute the given area (78.5 cm²) into the formula: 78.5 = π * r².
Step 3: To isolate r², divide both sides of the equation by π: r² = 78.5 / π.
Step 4: Calculate the value of 78.5 / π using a calculator. This gives you r² = 25.
Step 5: To find the radius (r), take the square root of r²: r = √25.
Step 6: Calculate the square root of 25, which is 5. Therefore, the radius is 5 cm.
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