1. WARM UP 1)Find the area of an equilateral triangle with radius 2)Find the area of a regular hexagon with perimeter 72. 3)Find the area of a square with apothem 5.

2. Section 11.5 Circumferences and Areas of Circles

3. Circumference

4. AREA of a CIRCLE

5. Find the circumference of a circle with an area of 72π. A = 72π

6. Wrestling Mat A Sallies wrestling mat is a square with 40 ft sides. A circle 28 ft in diameter is painted on the mat. No wrestling is allowed outside the circle. Find the area of the part of the mat that is NOT used for wrestling. 40 ft 28 ft Find the area of the square and TAKE OUT the area of the circle.

7. If a bicycle tire has a diameter of 26 inches, how far does it travel in 1000 revolutions of the tire? HINT: You need to use circumference! This is one revolution 81.68 ·1000 = 81,680 inches

8. Pizza – my favorite If 6 oz are needed to make an 8-inch pizza, how much dough will be needed to make a 16-inch pizza? Hint: compare the areas!

9. Target Practice A target consists of four concentric circles with radii 1, 2, 3, and 4. Find the area of the bull’s eye and of each ring of the target. To get the 2 nd ring you must subtract out the first ring. To get the 3 rd ring you must subtract out the second ring. To get the 4 th ring you must subtract out the third ring.

10. Practice Page 447 #1 – 12 Make the chart for #1-8 Challenge Problems: Page 449 #14, 21, 22

11. Cool Circumference Video