Math 8 (Period 1)

Lines 5-1

 This is important vocabulary that you MUST know:

Parallel lines: Lines in the same plane that will NEVER intersect
On the coordinate plane, they have the same slope (constant rate of change)

Perpendicular lines; Lines in the same plane that intersect at a right angle ( 90 degrees)
On a coordinate plane, their slopes are opposite sign reciprocals

Transversal: A line that intersects two or more lines

This transversal creates angles that have specific names:

Interior Angles: Angles on INSIDE the two lines that are transversed (intersected)

Exterior Angles: Angles on OUTSIDE of the two lines that are transversed (intersected)

Alternate Interior Angles: Interior Angles that are on opposite sides of the transversal

Same Side Interior: Interior angles that are on the SAME SIDE of the transversal

Corresponding Angles: Angles that are in the SAME position on different lines with the same position with respect to the transversal

If the lines intersected by the transversal are PARALLEL, there are certain relationship between the angles:

Alternate Interior Angles are CONGRUENT

Corresponding Angles are CONGRUENT

Same Side Interiors are Supplementary (The sum of the degrees of two angles that are supplementary is 180 degrees)

Vertical Angles are CONGRUENT

Adjacent Angles are SUPPLEMENTARY (they form a STRAIGHT ANGLE)

The last two are sometimes harder for students to recognize:
Alternate Exterior Angles  are CONGRUENT
Exterior Same Side angles are SUPPLEMENTARY