WEBVTT

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Here is the problem: A circle has diameter 15. Find its radius, diameter, circumference and area.

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Find the radius, diameter, circumference and area of a circle from any one of them.

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Radius from the diameter.

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Circumference.

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Area.

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So the answer is r equals 15 over 2, d equals 15, C equals 15pi approximately 47.1238898, A equals 225pi/4 approximately 176.7145868.

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Every measurement of a circle follows from its radius. The circumference grows in proportion to the radius and the area in proportion to its square.

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C/d equals 3.141592654 equals pi.

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A equals C times r/2 equals 176.7145868.