geometry vocab Flashcards
point
a specific location in space named by a letter
line
a set of points that extends indefinitely in opposite directions
plane
a flat 2D surface that extends indefinitely in all directions
line segment
part of a line with 2 endpoints
ray
part of a line with 1 endpoint extending indefinitely in opposite direction
angle
two rays with a common endpoint called a vertex
acute angle
less than 90 degrees
right angle
exactly 90 degrees
obtuse angle
greater than 90 degrees
straight angle
exactly 180 degrees
complementary angles
2 angles with a sum of 90 degrees
supplementary angles
2 angles with a sum of 180 degrees
vertical angles
congruent angles formed by intersecting lines
parallel lines
lines in same plane that never intersect
perpendicular lines
lines that intersect to form right angles
skew lines
lines in different planes that never intersect
transversal
a line that intersects parallel lines to form special angle pairs
corresponding angles
angles in the same position formed when a third line intersects 2 lines
alternate exterior angles
a pair of angles on the outer side of 2 lines cut by a transversal that are on opposite sides of the transversal
alternate interior angles
a pair of angles on the inner sides of 2 lines cut by a transversal that are on opposite sides of the transversal
polygon
closed plane figures whose sides are line segments
congruent figures
figures which are exactly the same
adjacent angles
angles that share a common ray
perimeter
the distance around a figure
circumference
the distance around a circle
area
the number of square units inside a plane figure
