1. 6.12 Solve problems involving the circumference &/or area of a circle when given the diameter or radius. Derive approximations for pi(π) from measurements for circumference & diameter, using concrete materials & computer models

2. 6.12 vocabulary pg 62 approximation An inexact result adequate for a given purpose ratio A comparison of two numbers by division. Example: The ratio 2 to 3 can be expressed as 2 out of 3, 2:3, or 2/3. circumference The distance around the outside of a circle (like perimeter) distance is a little over 3 times the diameter pi The ratio of the circumference of a circle to the diameter of a circle; equal to the fraction 22/7; often written as the approximation 3.14 radius The distance from the center of the circle to any point on the circle (half diameter) diameter The distance across a circle through the center (double radius) Pg 61 6.12 Directions 1.DR your circle If Radius given, double for diameter If Diameter given, halve for radius Ex- 2.Determine what is being asked for, AREA or CIRCUMFERENCE 3. Write the formula and take one step at a time AreaCircumference A= π x r x r C= π x d A= πr² C= πd A= 3.14 x 5² C= 3.14 x 10 A= 3.14 x 25 C= 31.4 in A= 78.5 in ² D- 10 R-5 5 in 10 in D- 10 R-5

3. Practice Area 6.12 pg 64Pg 63 Practice Circumference