Geometry Midterm Review Sheet
**Parallel lines have same slopes
**Perpendicular lines have opposite reciprocal slopes
Coordinate Plane
**Horizontal lines have slopes that equal zero.
Vertical lines have undefined slopes.
All triangles add up to 180 degrees
Parallel Lines – lines that go forever without touching
Skew Lines – lines that do not intersect and do not run in the same direction, they are on
different planes
Parallel Planes – planes that do not intersect
Transversal – A line that crosses 2 or more parallel lines.
Complementary Angles – add up to 90 degrees
Supplementary Angles – add up to 180 degrees
Vertical Angles – are congruent
Linear Pair – adjacent angles that form a straight angle (2 angles equal 180 degrees)
Types of angles
o Acute – from 0 – 90 degrees
o Right – exactly 90 degrees
o Obtuse – from 90 - 180 degrees
Corresponding Angles – are congruent
Alternate Interior Angles - are congruent
Alternate Exterior Angles – are congruent
Same – Side Interior Angles – are supplementary (add to 180)
Isosceles Triangle –
o Has 2 equal sides
o The 2 base angles are equal
Right Triangle –
o Legs are the sides that form the right angle
o Legs are perpendicular
o Hypotenuse is the side across from the right angle
Scalene Triangle – no sides are congruent
Equilateral Triangle – all sides are congruent
How to Prove Congruent Triangles:
1) SSS
2) SAS
3) AAS
4) ASA
Triangles: the 2 smaller sides of a triangle have to add up to be bigger than the 3rd side.
Median – connects the vertex to the midpoint of the opposite side
Altitude – starts at vertex and intersects the opposite side perpendicularly (90 degree
angle)
Angle bisector – segment that has one endpoint at a vertex and bisects an angle of a
triangle
Perpendicular bisector – line/segment that is perpendicular to a side and passes through
that side’s midpoint
Quadrilateral – a polygon with 4 sides
Parallelogram – Opposite sides are parallel
1) Opposite angles are congruent
2) Opposite sides are congruent
3) Consecutive angles are supplementary (add to 180)
4) Diagonals bisect each other
Rectangle –
1) All parallelogram rules
2) Four 90 degree angles
3) Diagonals are congruent
Rhombus –
1) All parallelogram rules
2) All 4 sides are congruent
3) Diagonals bisect the angles
4) Diagonals are perpendicular
Square –
1)
2)
3)
4)
5)
6)
All parallelogram rules
Four 90 degree angles
Diagonals are congruent
All 4 sides are congruent
Diagonals bisect the angles
Diagonals are perpendicular
Trapezoid – not a parallelogram because the a trapezoid only has 1 set of parallel sides
Isosceles Trapezoid – the 2 non parallel sides and base angles are equal