Basic Geometry Vocab

two rays that share the same endpoint and extend in opposite directions to form a line

two angles whose measurements add up to 180 degrees

measurable length, measurable width, no measurable depth; named with 3 capital letter (representing the names of the 3 points on the same line) and the word plane in front

two angles whose measures add up to 90 degrees

a=a

a=b b=a

If a=b and b=c then a=c

If a=b and a+c=d then b+c=d

If a=b then a+c=b+c

If a=b then a-c=b-c

if a=b then a*c=b*c

If a=b then a/c = b/c

to cut into 3 congruent parts

two planes that do not intersect

no measurable length, no measurable width, no measurable depth, named with one capital letter

measurable length, no measurable width, no measurable depth; named with 2 capital letters (representing the names of 2 points on the line) and a symbol of a line above the letters, or with one cursive small letter

points, segments, or rays on the same line

that portion of a line with 2 distinct endpoints; named with 2 capital letter (the names of the endpoints) and a symbol of a segment above the letters

a line that intersects 2 or more lines

the angles formed when 2 lines are cut by a transversal and correspond to the same position at the points of intersection

a triangle with 3 congruent sides

a triangle with 3 acute angles

a triangle with one right angle

a triangle with one obtuse angle

two coplanar lines that meet to form a right angle

to have the same measure

an angle that measures 180 degrees

an angle that measure more than 90 degrees but less than 180 degrees

points, lines, segments, or rays on the same plane

an angle that measures 90 degrees

an angle that measures less than 90 degrees

a real number from 0 to 180, representing the measure of the angle using a protractor; named with a non-capital letter m in front of the name of the angle

the figure created when 2 rays share the same endpoint; named with 3 letters (the first letter is the name of a point on one side, the second letter is the name of the shared endpoints, and the third letter is the name of a point on the other side) and an angle sign in front of the letters or a number with the angle sign in front of the number

a point that bisects a segment If A is midpoint of line CD then CA=AD

a real number representing the length of a segment--written with 2 capital letter (the names of the endpoints) AB=5 the length of segment AB is 5 units

the angles formed when 2 lines are cut by a transversal and are between the lines, on opposite sides on the transversal and ay different points of intersection

the angles formed when 2 lines are cut by a transversal and are outside the lines, on opposite sides of the transversal and at different points of intersection

the angles formed when 2 lines are cut by a transversal and are between the lines, on the same side of the transversal and at different points of intersection

a triangle with 3 non-congruent sides

a triangle with 2 congruent sides

a triangle with 3 congruent ANGLES *DO NOT MIX THIS ONE UP WITH THE EQUILATERAL TRIANGLE!

If lines AB=CD and lines CD=XY then lines AB=XY

If lines AB=CD then lines CD=AB

lines AB=AB

two non-adjacent angles formed when 2 lines intersect