Two identical solid hemispheres are placed flat side to flat side, forming a sphere. Find the percentage of the sphere’s total surface area that comes from the flat circular faces of the hemispheres before joining.
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Correct answer: C
Explanation
Given:
Two identical hemispheres combine to form a sphere.
According to the formula:
Total surface area of the sphere = 4πr²
Area of the flat circular face of a hemisphere = πr²
Area of the flat circular faces of the two hemispheres = 2 × πr²
Total surface area of the sphere = 4πr²
Percentage = (2πr² / 4πr²) × 100 = 50%