Make sure the "divide the scale" box is checked. Drag the green point down to the ruler to measure the diameter of the circle using centimeters. What is its diameter? Measure to the hundredths place. Record on your data sheet.[br][br]Drag the red point P to roll and straighten the circumference, distance around the circle. Record the measure of the circumference on your data sheet. Use the Zoom In, Zoom Out and Move tools if necessary.[br][br]Change the diameter of the circle twice to fill out the chart on your data sheet. Calculate the value of:[br]circumference ÷ diameter. Answer the questions on your recording sheet.[br]

Anthony Or. GeoGebra Institute of Hong Kong.[br]orchiming@gmail.com