If a circle's area is 78.5 cm², what is its radius?

₹0.0

Question: If a circle\'s area is 78.5 cm², what is its radius?

Options:

Correct Answer: 7 cm

Solution:

Area = πr², so r = √(Area/π) = √(78.5/π) ≈ 5 cm.

If a circle's area is 78.5 cm², what is its radius?

If a circle's area is 78.5 cm², what is its radius?

Step 1: Understand the formula for the area of a circle, which is Area = πr².
Step 2: We know the area is 78.5 cm², so we can set up the equation: 78.5 = πr².
Step 3: To find the radius (r), we need to isolate r. First, divide both sides by π: r² = 78.5/π.
Step 4: Now, take the square root of both sides to solve for r: r = √(78.5/π).
Step 5: Use the value of π (approximately 3.14) to calculate: 78.5/π ≈ 25.
Step 6: Now, find the square root of 25: r = √25 = 5 cm.

Area of a Circle – Understanding the formula for the area of a circle (A = πr²) and how to manipulate it to find the radius.
Square Root Calculation – Applying the square root function correctly to derive the radius from the area.
Use of π – Recognizing the value of π in calculations and its significance in geometry.