Presentation on theme: "Geometry Notes Sections 3-1. What youll learn How to identify the relationships between two lines or two planes How to name angles formed by a pair of."— Presentation transcript:
Geometry Notes Sections 3-1
What youll learn How to identify the relationships between two lines or two planes How to name angles formed by a pair of lines and a transversal
RELATIONSHIPS BETWEEN LINES 2 Lines are either CoplanarNoncoplanar Two noncoplanar lines that never intersect are called SKEW lines. The lines intersect once (INTERSECTING LINES) The lines never intersect (PARALLEL LINES) The lines intersect at all pts (COINCIDENT LINES) This is what well study in Chapter 3
Lets start with any 2 coplanar lines Any line that intersects two coplanar lines at two different points is called a transversal transversal 8 angles are created by two lines and a transversal Interior Angles 3, 4, 5, 6 4 Exterior Angles 1, 2, 7, 8
Consecutive Interior Angles We have two pairs of interior angles on the same side of the transversal called Consecutive Interior Angles or same-side interior angles The two pairs of consecutive (same-side) interior: 3 & 5 and 4 & 6
Alternate We have two pairs of interior angle on opposite sides of the transversal called Alternate Interior Angles Alternate Interior Angles Interior Angles The two pairs of alternate interior angles are: 3 & 6 and 4 & 5
Alternate Exterior Angles The two pairs of Alternate Exterior Angles 1 & 8 and 7 & 2 We have two pairs of exterior angles on opposite sides of the transversal called Alternate Exterior Angles
1 Corresponding Angles There are four pairs of Corresponding Angles 1 & 5, 2 & 6, 3 & 7, and 4 & 8 Corresponding Angles are in the same relative position
Find an example of each term. Corresponding angles Alternate exterior angles Linear pair of angles Alternate interior angles Vertical angles
Now if the lines are parallel... All kinds of special things happen... The corresponding angles postulate (remember these are true without question) says... If two parallel lines are cut by a transversal, then the corresponding angles are congruent The four pairs of Corresponding Angles are
Tell whether each statement is always (A), sometimes (S), or never (N) true. 2 and 6 are supplementary 1 3 m 1 m and 8 are supplementary m 5 = m 4
Find each angle measure.
Determine whether or not l 1 l 2, and explain why. If not enough information is given, write cannot be determined.
Have you learned.... How to identify the relationships between two lines or two planes How to name angles formed by a pair of lines and a transversal Assignment: Worksheet 3.1