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Geometry terminology
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Gravity
Key Concepts:
Terms in this set (48)
Acute angle
angle whose measure is greater than 0 and less than 90
Acute triangle
triangle that has three acute angles
Adjacent angles
angles that share a common vertex, a common side and no common interior points (they do not overlap)
Altitude of a triangle
a line segment extending from any vertex of a triangle perpendicular to the line containing the opposite side
Angle bisector
a ray whose endpoint is the vertex of the angle and which divides the angle into two congruent angles
Bisector of a line segment
any line or subset of a line that intersects the segment at its midpoint.
Complementary angles
two angles the sum of whose measures is 90.
Congruent angles
angles of the same measure
Congruent segments
segments of the same length
Congruent triangles
triangles whose corresponding angles and sides are congruent
Equiangular triangle
triangle which has three congruent angles
Equilateral triangle
triangle with three congruent sides
Isosceles triangle
a triangle with two congruent sides
Linear pair
adjacent angles whose noncommon sides are opposite rays( form a straight line). The sum of the measures of the angles in a linear pair is 180. unlike supplementary angles, a linear pair MUST be two adjacent angles
Median of a triangle
a line segment extending from any vertex of a triangle to the endpoint of the opposite side
Midpoint of a line segment
the point on that line segment that divides the segment two congruent segments
Perpendicular bisector of a segment
a line or subset of a line that bisects the segment and is perpendicular to the segment
Obtuse angle
an angle whose measure is greater than 90 and less than 180
Perpendicular lines
two lines which intersect to form right angles
Right angle
an angle whose measure is 90
Right triangle
a triangle containing on right angle
Scalene triangle
a triangle with no congruent sides
Straight angle
an angle whose measure is 180
Supplementary angles
two angles the sum of whose measure is 180. Supplementary angles need not be adjacent
Vertical angles
two nonadjacent angles formed by two intersecting lines
A point is
usually labelled with a capital letter.
A line passing through two points, A and B, can be called
line AB or line BA and extends indefinitely in both directions.
A plane is
a flat surface and extends indefinitely.
Collinear
Points that all lie on a single line
An intersection point is
where two lines meet
Concurrent is when
More than two lines that meet at the same point
line segment (or interval)
is part of a line with a fixed length and end points.
If the end points are A and B,
then it would be named segment AB or segment BA (or interval AB or interval BA).
A ray AB is
a part of a line with one end point A and passing through point B.
The vertex.
When two rays (or lines) meet, an angle is formed at the intersection point
Arms of the angle
rays
An angle
is named using three points, with the
∠BCA or a° vertex as the middle point. A common type of
notation is ∠ABC or ∠CBA.
Lower-case letters
are often used to represent the number of
degrees in an unknown angle.
Parallel lines
two lines that are in the same plane, but do not intersect can be written as AB ‖ CD
A reflex angle
is an angle between 180° and 360°
A revolution
is an angle that equal 360°
A protractor
tool for measuring angles in degrees
Adjacent angles
are side by side and share a vertex and an arm.
Complimentary angles
add to 90°
Supplementary angles
add to 180°
Angles in a revolution
add to 360°
Vertically opposite angles are formed.
when two lines intersect. The opposite angles are equal.
Lines that are perpendicular
meet at 90°.
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