10.7 Circumference and Area: CIRCLES
Pre-Algebra
Sir Cumference and the Dragon of Pi
Circumference of Circles
Parts of a circle!
Circumference The distance AROUND the circle
Center The given point in the very middle
Radius The distance from the CENTER to ANY point on the
circle
Diameter The distance across the circle THROUGH its center
Circumference
FormulasC=2 r
C = d
C is Circumference is 3.14 r is radius d is diameter
Area
A = r2
A is the Area Pi is 3.14 R is the radius squared
SHOW ALL OF YOUR WORK EVERY TIME!!!!!
FORMULAWORKANSWERUNITS
Examples
1. Find the circumference and area of the circle if: r = 2 cm
Examples
2. Find the circumference and area of the circle if: d = 6 in
Find the circumference and area to the nearest tenth.
3.
12 in.
Find the circumference and area to the nearest tenth.
4.
7.1 m
Find the circumference and area to the nearest tenth.
5.
11 ft
Find the circumference and area to the nearest tenth.
6.
8.3 cm
10.7 Study Guide and InterventionWrite ALL formulas EVERY time and
SHOW all work!
Homework!Write ALL formulas EVERY time and SHOW all
work!
Do not just Guess!!! Show WORK!!!!