###
If two parallel planes are cut by a third plane,

then the lines of intersection are parallel

###
alternate interior angles

two nonadjacent interior angles on opposite sides of the transversal

###
Same side angles

two interior angles on the same side of the transversal

###
corresponding angles

two angles in corresponding positions relative to the two lines

###
If two parallel lines are cut by a transversal,

then corresponding angles are congruent

###
If two parallel lines are cut by transversal,

then alternate interior angles are congruent

###
If two parallel lines are cut by a transversal,

then same side interior angles are supplementary

###
If a transversal is perpendicular to one of two parallel lines,

then it is perpendicular to the other one also

###
If two parallel lines are cut by a transversal,

then correspondung angles are congruent

###
If two lines are cuy by a transversal and corresponding angles are congruent,

then the lines are parallel

###
If two lines are cuy by a transversal and alternate interioir angles are congruent,

then the lines are parallel

###
If two lines are cut by a transversal and same side interior angles are supplementary,

then the lines are parallel

###
In a plane two lines perpendicular to the same line

are parallel

###
Through a point outside a line,

there is exactly one line parallel to the given line

###
Through a point outside a line,

there is exactly on eline perpendicular to the given line

###
Two lines parallel to a third line

are parallel to each other

###
Scalene

no sides congruent

###
isosceles

at least two sides congruent

###
equiangular

all angles congruent

###
The sum of the measure of the angles

of a triangle is 180

###
If two angles of one triangle are congruent to two angles of another triangle,

the the thrid angles are congruent

###
The acute angles of a right triangle

are complementary

###
The measure of an exterior angles of a triangle equals

the sum of measures of the two remote interioir angles

###
The sum of the meausre of angles or a convex polygon with n sides

is (n-2)180.

###
The sum of the measures of the exterior angles of any convex polygon,

one angle at each vertex, is 360

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