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Circle Basics

100

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). 

200

What is the name of the distance from the center to the edge

Radius

300

Whats the formula for circumference?

C=2PiR

400

What do you call a line segment that passes through the center?

Diameter

500

If the radius is 5 units, what is the diameter?

10 units

Standard Equation

100

What is the standard form of a Circles Equation?

(x-h)^2+(y-k)^2=r^2

200

In the equation 

(x+3)^2 + (y-2)^2 = 16, what is the center

(-3, 2)

300

In the equation 

(x+3)^2 + (y-2)^2 = 16, what is the radius

4

400

Rewrite this in standard form: x^2 + y^2 = 25

Center: (0,0), Radius 5

500

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)

Challenge Round

100

(x-2)^2 + (y+1)^2 = 9

what's the radius?

3

200

What is the area of a circle with radius 6?

Pi x 36 = 36pi

300

Find the equation: Center (4, -5) radius 2

(x-4)^2 + (y+5)^2 = 4

400

Whats the midpoint of a diameter from (2,4) to (8,10)

5,7

500

What does a sphere look like from a 2d perspective

cirelcell