WEBVTT

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Here is the problem: A circle has diameter 7. 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 7 over 2, d equals 7, C equals 7pi approximately 21.99114858, A equals 49pi/4 approximately 38.48451001.

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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 38.48451001.