1)Create a circle with a diameter of 6 cm. 2) Using a ruler, divide the circle into 8 congruent sectors. 3)Cut out the sectors and arrange them to form a parallelogram. 4)Create another circle with a diameter of 8 cm. 5)Using a ruler, divide the circle into 24 congruent sectors. 6)Cut out the sectors and arrange them to form an approximate parallelogram. 7)What do you notice about the 2 parallelograms? = the greater number of sectors, the more the shape looks like rectangle

The greater the number of sectors, the more the shape looks like a rectangle. The sum of the 2 longer sides of the rectangle is equal to the circumference, C. What is circumference?= the perimeter of a circle What is “r” equal to?= radius, ½ the diameter of a circle r C2C2 So, each longer side, or the base of the rectangle is one-half the circumference or C 2

C = 2 r so the base of a rectangle = 2 r 2 = r Each of the two shorter sides is equal to the radius. r r r 2 r

Area of a circle: A = r 2 The face of a dime has a diameter of 1.8 cm. 1)Calculate the answer to two decimal places. 2)Estimate to see if the answer is reasonable. Text pages