9.1 - Circumference of Circles
9.2 - Areas of Circles
9.3 - Perimeters and Areas of Composite Shapes
100
What is the diameter of this circle?
d = 14
*The diameter is twice the size of the radius.
*The radius is half the length of the diameter.
100
What is the formula for finding the area of a circle?
A = pir^2
100
What two formulas do you need to know in order to solve this perimeter problem?
Perimeter of a triangle:
P = side 1 + side 2 + side 3
Semi-circle perimeter (circumference):
C=(pid)/2
200
What is the radius of this circle?
r = 10
200
Find the area of the circle.
A = pir^2
A = pi(7)^2
A = (3.14)(49)
A = 153.86 cm^2
200
Solve for the area of this shape.
A=(pir^2)/2
A=(pi(5)^2)/2
A=39.25
A = 1/2bh
A=1/2(6)(8)
A=24
A = 39.25+24 = 63.25
300
Find the circumference of the pool.
C = pid
C= 43.96 ft
300
Find the area of the circle
A = pir^2
A = pi(4.5)^2
A = (3.14)(20.25)
A = 63.59 cm^2
300
Find the area of this shape
A = l x w
A = 2 x 2 = 4
A = pir^2
A = pi(1)^2
A = pi
A = (2)pi = 6.28
A = 4 + 6.28 = 10.28
400
Find the perimeter of the semicircular shape.
C = (pid)/2 + d
C = 28.98 cm^2
400
Find the area of the semicircle.
A = (pir^2)/2
A = (pi(4)^2)/2
A = (16pi)/2
A = 8pi
A = (8)(3.14)
A= 25.12 m^2
400
Find the area and perimeter of this shape.
A = 5x5 = 25
A = 7x16 = 112
A = 112+25 = 137
P = 7+5+5+5+11+7+16 = 56
500
Find the diameter of the sewer lid.
C = pid
122 = pid
122/3.14 = d
d = 38.86
500
Find the area of the circle.
A = pir^2
A = pi(1)^2
A = 1pi
A = 3.14 cm^2