5. Circle
• Diameter
d=2r diameter
• Circumference
ra
di
us
C=2πr
• Area
A=πr2
** Always use the π button on the calculator;
even when the directions say to use 3.14.
6. Example: Find the perim. & area of the figure.
• P=2l +2w
P=2(5in)+2(3in)
P=10in+6in
5 in P=16in
3 in
• A=lw
A=(5in)(3in)
A=15in2
7. Ex: Find the perim. & area of the figure.
• P=4s
P=4(20m)
P=80m
20 m
• A=s2
A=(20m)2
A=400m2
8. Ex: Find the perim. & area of the figure.
• P=a+b+c
P=5ft+7ft+6ft
5 ft
P=18 ft
4 ft
7 ft
6 ft • A= ½ bh
A= ½ (7ft)(4ft)
A= ½ (28ft2)
A= 14ft2
9. Ex: Find the circumference & area of the
circle.
• C=2πr
C=2π(5in)
n
10i C=10π in
C≈31.4 in
• A=πr2
A=π(5in)2
A=25π in2
A≈78.5 in2