Circumference
Which of these formulas can you use to find the circumference of a circle..
a] 𝛑r2
b] C2/4𝛑
c] C/d
d] 2𝛑r and 𝛑d
d] 2𝛑r
Which formula do we NOT use to find the area of a circle..
a] 𝛑r2
b] C2/4𝛑
c] 2𝛑r
d] Nice try, Mr. Davis, all of these formulas find area of a circle.
c] 2𝛑r is the formula for circumference
We shade in the circle when the value is..
a] included as a solution
b] not included as a solution
a] included as a solution
An expression has a solution.
a] False
b] True
a] False
Equations have solutions, not expressions.
The diameter of the circle is 10 m, what is the circumference in terms of pi?
10𝛑
Draw a circle with a radius of 2cm, find the area. Use 3.14 for pi.
𝛑r2 = 3.14 x 4 = 12.56cm2
Graph the real-life situation as an inequality.
Edwin wants to spend less than 5 dollars today.
x < 5
4(5 + a) = 28 (solve for a)
⅓y =11 [solve for y]
a = 2
y = 33
Using 3.14 for 𝛑, find the circumference of a circle that has a radius of 4in.
25.12in.
Draw a circle with a diameter of 16cm, find the area. Use 3.14 for pi.
3.14 x 82 = 3.14 x 64 = 200.96cm2
You must be at least 52 inches tall to get on this ride. If h is height, write an inequality that represents how tall you have to be to ride it. Provide an example of a solution to the inequality.
h is greater than or equal to 52. h could be 54 inches.
Write an expression for the following real-life scenario..
An electrician charges a one-time service fee of 95 dollars plus 100 dollars each hour.
95 plus 100h or 100h plus 95
A train travels around a Christmas tree in a circle. The train track measures 13.5 feet in diameter. What is the distance (in feet) that the train travels?
42.39 feet
Find the area, to the nearest hundredth, of a circle that has a circumference of 19 centimeters. Use 3.14 for pi.
A = C2/4𝛑
A = 192 / [4 X 3.14] = 361/[4 X 3.14] = 28.74cm2
Solve the inequality and graph the solution.
23 more than 5 times x is less than or equal to 48.
x is less than or equal to 5.
Write and solve an equation for the following real-life scenario..
An electrician charges a one-time service fee of 95 dollars plus 100 dollars each hour. The job will take him 4.5 hours to complete.
95 plus [100][4.5] = 95 plus 450 = 545 dollars
A circular fountain is in the center of a park. The distance across the fountain (through the center) is 12 meters.
a. What is the radius of the fountain?
b. What is the exact circumference of the fountain in terms of π?
a. Radius is half of diameter, which means that it is 6 meters.
b. πd
The face of a clock has a circumference of 14𝛑 inches. What is its area? Use 3.14 for 𝛑.
A = C2/4𝛑
A = [14 X 3.14]2 / [4 X 3.14]
A = 153.86 in2
Shawna has $60 right now, but is saving up for something that costs $145. She earns $14.50 per hour at her job. What is the least number of full hours, h, she needs to work to afford the item?
6 hours.
-1/2t + 6 = 16
t = -20