Circle Basics
What is the definition of a circle?
A circle is the set of all points in a plane that are the same distance from a fixed point (called the center).
What is the standard form of a Circles Equation?
(x-h)^2+(y-k)^2=r^2
what's the radius?
What is the name of the distance from the center to the edge
Radius
In the equation
(x+3)^2 + (y-2)^2 = 16, what is the center
(-3, 2)
What is the area of a circle with radius 6?
Pi x 36 = 36pi
Whats the formula for circumference?
C=2PiR
In the equation
(x+3)^2 + (y-2)^2 = 16, what is the radius
4
Find the equation: Center (4, -5) radius 2
(x-4)^2 + (y+5)^2 = 4
Diameter
Rewrite this in standard form: x^2 + y^2 = 25
Center: (0,0), Radius 5
Whats the midpoint of a diameter from (2,4) to (8,10)
5,7
10 units
True or False:
(x-4)^2 + (y+1)^2 = 0 is a valid circle. If false, why not
False, the radius = 0 (not a circle)
What does a sphere look like from a 2d perspective
cirelcell