 Please start Bellwork #84  HW, red pen, book out

Area: Circles Lesson 10-3 p.514

Circles  To find the area of a circle, use this formula:  Remember that is 3.14 and r is the radius of the circle. Remember to square the radius- -not double it.

Example To find the area of this circle, square the radius (3) and multiply by pi. 3 ft A = 3.14 (3 2 ) = 3.14 (9) = ft 2

Try This  Find the area: 12 feet

Try This  Find the area: 12 feet A = ft 2

Try This  Find the area: 16 m

Try This  Find the area: 16 m m 2

Example  Some unusual shapes have circles as part of the figure. How would you find the area of this shape?

Example  You would find the area of the circle and divide it in half. Then find the area of the rectangle and add it to the area of the half circle.

Example  Let’s try it. Circle: A = 3.14 (3.5) 2 A = 3.14 (12.25) A = Take half since it is a half circle. A = yds 2 Rectangle: A = bh A = 10 (7) = 70 Add the two areas: = yds 2 10 yards 7 yds

Try This  Find the area. 6 m

Try This  Find the area. 6 m m 2

Try This  Find the area: 12 miles 4 mi

Try This  Find the area: 12 miles 4 mi A = mi 2

Challenge problem  Find the area: 6 mm12 mm

Challenge problem  Find the area: 6 mm12 mm A = mm 2

Agenda  Pp.517  #4-7, 10-15