lesson e: circumference of circles objective: to use formulas to find the circumference of circles
TRANSCRIPT
Lesson E: Circumference of
CirclesObjective: To use formulas to find the
circumference of circles.
The circumference of a circle is the distance around the circle.
Circumference:
The number is used when finding area
and circumference.
An approximation of is __________ or
_________.
Examples: Find the circumference of each circle below. Do not use an approximation.
Examples: Find the circumference of each circle below. Use the approximations listed below for .
1) 2)
3) Use 22/7 as an approx.
4) Use 3.14 as an approx.
14 in8 in
πͺ=π π πͺ=
πππ
βππ
πͺ=πππ
βπππππ
πͺ=ππππ .
πͺ=π π πͺ=π .ππβππ
πͺ=ππ .ππππ .
Complete #4. Then complete #3. No calculator for #3!!
5. If the circumference of a circle is , find the length of the radius of the circle.
6. If the circumference of a circle is , find the length of the radius of the circle. Use 3.14 for . Round your answer to the nearest tenth.
πͺ=π π πππ =π π
ππππ=πππππ=π
πͺ=π π ππ=π .πππ
π .π ππβππ .ππβπ
π π
π .ππ π .ππ
7. If the circumference of a circle is , find the length of the radius of the circle. Use 22/7 for .
8. The circle is inscribed in a square. The perimeter of the square is 60 inches. Find the circumference of the circle. Leave in terms of (no approximation).
πͺ=π π ππ=
πππ
π
πππ
βππ=πππ
π βππππ
ππππ=π
π ππ ππππ=π
πππ
βπππ
=π π
π
Multiply by the reciprocal!
Try on your own first! Take about 5 minutes.Now get together with a group to try working through it if you had trouble.
How do you move a fraction to the other side?
9. The circle is circumscribed about a square. The circumference of the circle is 2 ft. Find the length of the diagonal of the square.
Try on your own first!
Now get together with a group to try working through it if you had trouble.
Circles Worksheet E
Assignment
Finish Circles Worksheet E for homework (#7-12)