Key vocabulary over statistics and probability.

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Sum of Interior Angles

all inside angles added up

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measure of an interior angle of a regular polygon

"the sum of all angles divided by the number of angles"

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regular polygon

a polygon with equivalent sides and angles

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formula for "Sum of interior angles"

(n - 2)180

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sum of exterior angles

all outside angles added up

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formula for the sum of exterior angles

always 360

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measure of an exterior angle of a regular polygon

"the sum of all angles divided by the number of angles"

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formula for an exterior angle of a regulary polygon

360/n

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point of concurrency

where three lines meet/intersect

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"regular" polygon

equal sides and equal angles

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Centroid of a triangle

point of concurrency of the medians; always inside the triangle

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median

cuts a line segment in half

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Incenter of a triangle

point of concurrency of the angle bisectors; always inside the triangle

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angle bisector

cuts an angle in half

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Circumcenter of a triangle

point of concurrency of perpendicular bisector; can be inside or outside of the triangle

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perpendicular bisector

A line that is perpendicular to a segment at its midpoint.

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Orthocenter of a triangle

point of concurrency of the altitudes; can be inside or outside of the triangle

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altitude

goes from the vertex to the opposite side, forming a 90 degree angle

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vertical angles

a pair of opposite congruent angles formed by intersecting lines

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complementary angles

Two angles whose sum is 90 degrees

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supplementary angles

Two angles whose sum is 180 degrees

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distance formula

d = √[( x₂ - x₁) + (y₂ - y₁)]

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midpoint formula

M = [ (x₁ + x₂) / 2, (y₁ + y₂) / 2 ]

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perpendicular lines

lines that form a 90 angle; their slopes are opposite reciprocals.

Ex: if the slope of a line is 1/2, the slope of the perpendicular line is -2.

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parallel lines

lines that have the same slope, so they never intersect

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perimeter

the some of all sides

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area

the number of square units needed to cover a flat surface