Exploring Circles

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How to Draw a Circle.

Spend some time familiarizing yourself with the tools that are available in this applet.

(1). Then draw and label Circle A, with a diameter of 6 cm.

(2). Draw and label Circle B, with a radius of 5 cm. 

(3). Draw and label Circle C, with a radius that is equal to Circle A’s diameter.

(4). Draw and label Circle D, with a diameter that is equal to Circle B’s radius.

(5). Use a compass app below to recreate one of these designs.

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Draw Radius and Diameter of a Circle.

  • Use the geometric tool in the applet below to draw a circle. ​
  • Draw and measure a radius and a diameter of the circle.

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Name the Radius and Diameter of a Circle.

Here is a circle with center H and some line segments and curves joining points on the circle.

(1). Identify example(s) of a diameter. Explain your reasoning.

(2). Identify example(s) of a radius. Explain your reasoning.

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Sort these pictures into two groups.

Explain why you sorted the objects like you did.

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On January 3rd, Earth is 147,500,000 kilometers away from the Sun. On July 4th, Earth is 152,500,000 kilometers away from the Sun. The Sun has a radius of about 865,000 kilometers.

Could Earth’s orbit be a circle with some point in the Sun as its center? Explain your reasoning.

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Lin measured the diameter of a circle in two different directions. Measuring vertically, she got 3.5 cm, and measuring horizontally, she got 3.6 cm. Explain some possible reasons why these measurements differ.