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How does the radius of a circle affect it's size?
Discover how the lenth of the radius affects the area and circumfance of a circles. Slide "r_1" to change the length of the radii of the circles. Slide "a" to change the lenght of r_2 in relation to r_1.

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  1. Fix a=1 and move r_1. What effect does this have on each circle? What happens to the areas of the circles? the circumfrence?
  2. Now fix r_1 and move a. What happens differently than in part 1?
  3. Based off your observations, what is "a"?
  4. Using your observations above and the standard equations for the area and circumfrence of a circle create a general formula to find the area and circumfrence of c_2 from c_1.
Area of a circle= &pi r2
Circumference of a circle= 2&pi r