2-2 Day 2 Parallel & Perpendicular Lines Objective: Students will apply knowledge of slopes to parallel and perpendicular lines and extension problems.
Parallel Lines Two lines with the same slope are said to be parallel lines. If you graph them they will never intersect. We can decide algebraically if two lines are parallel by finding the slope of each line and seeing if the slopes are equal to each other.
Parallel Lines The slope of the blue line is: -3/2 The slope of the red line is: -3/2 The slopes are EQUAL
Perpendicular Lines Perpendicular lines are lines that intersect in a right angle. We can decide algebraically if two lines are perpendicular by finding the slope of each line and seeing if the slopes are negative reciprocals of each other. This is equivalent to multiplying the two slopes together and seeing if their product is –1.
Perpendicular Lines The slope of the blue line is: ½ The slope of the red line is: -2 ½ ● -2 = -1 The slopes are OPPOSITE RECIPROCALS
Applications Slope: rise run
Application Rate of descent: It takes a skier 25 minutes to complete the course shown below. Find his average rate of descent in feet per minute. The rate of descent is: 140 ft. per minute
Application Rate of growth: A small business predicts sales according to a straight-line method. If sales were $85,000 in the first year and $125,000 in the third year, find the rate of growth in sales per year (the slope of the line). (1, 85000) (3, ) The company’s rate of growth is: $20,000 per year.
Homework: p.110 #46,48,52,56,58, 60,64,66,72,78,80