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Level 91

## Ignore words

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Circle
in a plane, the set of all points equidistant from a given point
Center
Each regular polygon has a center because it can be inscribed in a circle.
From center to a point on the circle.
congruent circles
circles with congruent radii
diameter
A straight line passing through the centre of a circle to touch both sides of the circumference.
Central Angle
an angle whose vertex is the center of the circle
semicircle
half of a circle
arc
part of a circle
minor arc
smaller than a semicircle; named by its endpoint with an arc symbol over the letters - ⌒
major arc
larger than a semicircle; named by its endpoints and another point between the endpoints on the arc with an arc symbol over the letters - ⌒
arcs of the same circle that have exactly one point in common
Circumference
2πr
P⌊
∏= 22/7= 3.14...
concentric circles
coplanar circles that have the same center
arc measure
always in degree
arc length
a fraction of the circumference
congruent arcs
arcs with the same measure or length
c
∏d or 2∏r
p
ns (number of sides ⋅ side length)
a
1/2⋅a⋅p (1/2⋅ apothem⋅ perimeter)
Sector of a Circle
region bounded by an arc of the circle and the two radii to the arc's endpoints; names using one arc endpoint, the center of the circle, and the other arc endpoint
segment of a circle
part of a circle bounded by an arc and the segment joining its endpoints
Area.
The space enclosed by a shape.
The distance from the center to the edge of a circle.
Formula to find diameter
Diameter = 2 x radius (d=2r)
Formula to find radius
Radius = diameter/2 (r=d/2)
Formula to find circumference
Circumference = 3.14 x diameter (C=3.14d)
Formula to find area
Area = 3.14 x radius squared