HardMath· Geometry and Trigonometry· Area and volume· MCQ
A right circular cone has a volume of cubic feet and a height of 9 feet. What is the radius, in feet, of the base of the cone?
A
B
C
D
Correct answer: A
Explanation
Choice A is correct. The equation for the volume of a right circular cone is . It’s given that the volume of the right circular cone is cubic feet and the height is 9 feet. Substituting these values for V and h, respectively, gives . Dividing both sides of the equation by gives . Dividing both sides of the equation by 9 gives . Taking the square root of both sides results in two possible values for the radius, or . Since the radius can’t have a negative value, that leaves as the only possibility. Applying the quotient property of square roots, , results in , or .
Choices B and C are incorrect and may result from incorrectly evaluating . Choice D is incorrect and may result from solving instead of .
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id cb_question_bank:8936ba3a-68ed-4a79-b894-5d790adff80e · question dc71597b · IBN 032655-DC
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