Day 7 WAE Circles center origin.notebook
November 25, 2013
Do Now
1) What is the formula for a) Area of a circle
b) Circumference of a circle
2) What do you think you need to graph a circle?
Writing Equation of and Graphing Circles
Objective: Students will learn how to write an equation of a circle and graph it.
Day 7 WAE Circles center origin.notebook
November 25, 2013
To write an equation of a circle the
formula is: x2 + y2 = r2
Center is at the origin (0, 0)
Radius is "r" Given the following equations state the center and the radius of each. 1) x 2 + y 2 = 16
2) x 2 + y 2 = 25
center: center:
radius:
radius:
Day 7 WAE Circles center origin.notebook
November 25, 2013
3) x 2 + y 2 = 100
4) x 2 + y 2 = 225
center: center: radius:
radius:
To write an equation of a circle you need:
a) the center
b) the radius
5)
Center: (0,0)
radius = 12
6)
Center: origin
radius =√ 3
Day 7 WAE Circles center origin.notebook
November 25, 2013
7)
Center: (0,0)
radius = 4
8)
Center: (0,0)
radius = 9
9)
Center: (0,0)
radius = 1
Graphing Circles
To graph a circle, you need the center and radius.
2) x2 + y2 = 25
1) x2 + y2 = 49
center:_____
radius:_____
center:_____
radius:_____
Day 7 WAE Circles center origin.notebook
3) x2 + y2 =16
center:_____
radius:_____
November 25, 2013
4) x2 + y2 = 9
center:_____
radius:_____
Exit Ticket:
Write an equation of a circle given the center and the radius:
1) Center: (0, 0) Radius: √12
What is the center and radius of the equation:
1) x2 + y2 = 64