Algebra 3 Warm-Up 1.5 Find the slope of each. 1.y = ¼ x – y = 5x x + 2y = 24  m = ¼  m = 5/3  m = -4

Algebra 3 Lesson 1.5 Objectives: SSBAT determine if 2 lines are perpendicular, parallel, or neither by looking at the slope of each line. SSBAT find the slope of a line parallel or perpendicular to a given line. Standards: M11.C.3.1.2

Review: What are Parallel Lines? What are Perpendicular Lines?  Lines that NEVER intersect  Two lines that form four 90◦ angles where they intersect

Example: y = 3x -4 y = 3x +7 Parallel Lines  Have the SAME slope

Perpendicular Lines  Slopes are Opposite Reciprocals One is positive and one is negative and they are reciprocals

Determine if the lines are Parallel, Perpendicular or Neither. 3. y = 7x + 19 and y = 7x + 3 m = 7 m = 7 The lines are PARALLEL.

Determine if the lines are Parallel, Perpendicular or Neither. 5. 2x + y – 2 = 0 and 4x + 2y + 18 = 0 y – 2 = -2x y = -2x + 2 m = -2 The lines are Parallel. 2y + 18 = -4x 2y = -4x – 18 y = -2x – 9 m = -2

7. Determine whether the line through P and Q is Parallel, Perpendicular or Neither to the line through R and S. P = (0, 8) Q = (-3, 5) and R = (2, -5) S = (3, -4) PQ  m = = 1 RS  m = = 1 The lines are Parallel because the slopes are the same.

 Complete Worksheet 1.5 in class #1, 4, 11 – 16 Homework Worksheet 1.5 #2, 3, 5 – 10