Classify and Measure Angles
polygon
a closed figure made up of line segments
circle
a figure with all of its points the same distance from the center
radius
a line segment from the center of a circle to any point on the circle
chord
a line segment that connects two points on a circle
diameter
a line segment that goes through the center of a circle to connect two points on the circle
side of a polygon
a line segment that is part of a polygon
secant
a line that goes through the circle at two distinct points on the circumference of a circle; the distance between the two points is considered a chord
tangent
a line that touches the exterior part of the circumference of a circle at exactly one point
regular polygon
a polygon whose sides are all the same length and all of its angles are the same measure
decagon
a polygon with 10 sides
triangle
a polygon with 3 sides
quadrilateral
a polygon with 4 sides
pentagon
a polygon with 5 sides
hexagon
a polygon with 6 sides
heptagon
a polygon with 7 sides
octagon
a polygon with 8 sides
nonagon
a polygon with 9 sides
concave
a shape with an indentation
convex
a shaped with no indentation
inscribed angle
an angle in a circle with a vertex on the circle and sides that are chords of the circle
central angle
an angle that has the center of a circle as its vertex
straight angle
an angle that measures exactly 180°
right angle
an angle that measures exactly 90°
acute angle
an angle that measures more than 0° but less than 90°
obtuse angle
an angle that measures more than 90° but less than 180°
major arc
an arc with a measure greater than 180 degrees
minor arc
an arc with a measure less than 180 degrees
semi-circle
an arc with a measure of 180 degrees
diagonal
an interior line that connects two vertices that are not already connected
vertical angles
angles that are opposite from one another at the intersection of two lines; vertical angles are congruent
interior angles
inside angles
perpendicular lines
lines that intersect and create right angles
transversals
lines that intersect two or more lines to create angles
parallel lines
lines that never cross one another and are the same distance apart at all times
intersecting lines
lines that share one point
exterior angles
outside angles
arc
part of the circumference of a circle between two points
circumference of a circle
the length around the exterior of a circle; measured in degrees in terms of an arc
intercepted arc
the part of the circumference of a circle that is bound by two endpoints of a chord, radius, secant line or tangent line
vertex
the point where two line segments, lines, or rays meet to form an angle
corresponding angles
two angles in the same position on different lines
adjacent angles
two angles that have a common vertex and side but are not overlapping
supplementary angles
two angles whose sum is 180°
complementary angles
two angles whose sum is 90°
alternate interior angles
two inside angles that lie on different sides of a transversal
alternate exterior angles
two outside angles that lie on different sides of a transversal