How can we help?

You can also find more resources in our Help Center.

25 terms

terms, theorems, postulates

concepts of basic geometry
STUDY
PLAY
parallel
coplanar lines that do not intersect; everywhere equidistant
perpendicular
intersecting at 90 degree angles
vertical angle theorem
Vertical angles are congruent
linear pair
two supplementary adjacent angles; opposite rays form a straight line
corresponding angles postulate
if // lines are crossed by a transversal, corresponding angles are congruent
alternate interior angles theorem
if // lines are crossed by a transversal, alternate interior angles are congruent
same side interior angle theorem
if // lines are crossed bya transversal, same side interior angles are supplementary
triangle sum theorem
the sum of the angles in a triangle is 180
Isosceles triangle theorem
the base angles of an isosceles triangle are congruent
reflexive property
AB = AB
transitive property
if A = B and B =C, then A = C
symmetric property
AB = BA
converse of Isosceles triangle theorem
If 2 angles in a triangle are congruent, then the sides opposite those angles are also congruent
180(n-2)
Sum of the degrees of a polygon with 'n' sides
angle bisector
line, segment, or ray that splits an angle into two equal angles
perpendicular bisector
line, segment or ray that intersects a segment at its midpoint at a 90 degree angle
midpoint
point on a segment exactly halfway between the endpoints
HL theorem
If the hypotenuse and one of the legs of a right triangle are congruent to the hypotenuse and one of the legs of another right triangle, then the triangles are congruent
SSS
If 3 sides of one triangle are congruent to 3 sides of another, then the triangles are congruent
SAS
If two sides and the INCLUDED angle of one triangle are congruent to two sides and the INCLUDED angle of another, then the triangles are congruent
ASA
If two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the triangles are congruent
AAS
If any two angles and one side of a triangle are congruent to two angles and a side of another triangle, then the triangles are congruent
vertex of isosceles triangle
angle formed by the two congruent legs
base angles
angles opposite the two congruent legs of an isosceles triangle
hypotenuse
longest side of a right triangle; opposite the right angle