Basic Terminology
Terms:
Point- A physical location in space that has no dimensions (length, width or height), labeled with capital letters
Line- An infinite set (collection) of points that extends forever in two directions.
Segment- bounded by two distinct points on a line, has a measurable length
Collinear- used to describe points which lie on the same line
Circle- the collection of all points that are a fixed distance away from a fixed point (its center)
Radius- The distance from the center of a circle to its edge
Diameter- a segment which passes through the center of a circle and has endpoints on the circle’s circumference
Ray- an infinite set of points that extends forever in one direction from a starting point Angle- the geometric object created by two rays with a common starting point. Vertex- point where two segments meet, also known as an “edge”
Degree- unit of measurement which measures the magnitude of an angle
Acute- angle has a measure between 0 and 90 ° Obtuse- angle has a measure between 90 and 180 ° Right- angle has a measure of 90°
Straight- angle has a measure of 180°
Reflex- angle has a measure between 180° and 360
Supplementary- angles whose measures add up to 180° . When placed adjacent to each
other, they would form a straight angle.
Complementary- angles whose measures add up to 90° . When placed adjacent to each other (so they share a common ray) they would form a right angle.
Adjacent- lying next to each other, angles which share a common ray Congruent- identical geometric figures
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Vertical angles- a pair of angles which have the same vertex and are on opposite sides of two intersecting straight lines
Bisector-A line, ray, or segment that passes through the midpoint of another segment.
Perpendicular- Any two lines, segments, or rays that intersect to form strictly 90° or right angles.
Midpoint-: The point on the line segment that divides it into two segments of equal length.
Perpendicular bisector- a line which passes through the midpoint of another line and forms right angles (is perpendicular to the line it bisects)
Parallel- when two lines never intersect, lines with the same slope and different y- intercepts
Isosceles- a triangles with two sides of equal length, base angles are congruent
Equilateral triangle- a three-sided figure whose sides are all the same length and whose angles all have the same measure