1. Goals The goals of this lab are to - determine the relationship between the radius and circumference of a circle - determine the relationship between the diameter and circumference of a circle - derive a formula that relates circumference to diameter

2. Background In your background paragraph, you should - define radius, circumference, diameter - introduce the mathematical relationship between the diameter and radius of a circle. EXAMPE In this lab, the circumference (c) will be defined as the distance around the outside of a circle. It will be measured in centimeters. The diameter (d) is defined as the longest chord (or the straight line distance from one side of the circle to the other that passes through the center). The radius (r) of the circle is the distance from the center of the circle to its edge. Both the radius and diameter will be measured in centimeters, and for any circle, 2r=d.

3. Materials / Procedure Ruler, various sized circles, string 1.Wrap the string around the outer edge of the circle. Mark where it meets the other end then lay it out flat to measure its length. This is the circumference. 2.Hold the string tight on one edge of the circle then stretch the string across the center. Make sure the string goes through the center of the circle. Mark the other side and measure. This is the diameter. 3.Divide the diameter by 2 to calculate the radius.

4. Data CircleDiameter (cm)Radius (cm)Circumference (cm) 1 2 3 4 5 6

5. Analysis Sample calculations:d = 2r 36cm = 2r r = 18cm Diameter Graph Calculations Slope:derived formula: %Error: Radius Graph Calculations Slope:derived formula: %Error:

7. Conclusion In a paragraph… -Restate goals -Introduce your newly derived formulas -Report results with their percent errors -Offer a source or error -Suggest a variation of this lab your reader could do to take the next step in their discovery of circles