Hi Welcome to MooMooMath. Today we are going to take a look at some special lines. First we are going to look at the slope of parallel lines, and this symbol in black represents parallel lines. ( looks like two tall L’s) Then we have the symbol for perpendicular lines, which looks like a large upside T. What do know about parallel lines? They are lines that never intercept, and when they are on a graph they are going to have the same slope because they are going to rise and run at the same rate. So if we look at line L it has a rise of two, and a run of two. So the slope is positive 1 ( 2/2 =1) If we look at the next line it also has a slope of 1 because you count up 2 and over 2 which simplifies to 1, so the lines are the same. Let’s next look at the next graph. The line L has the same slope which is up 2 and over 2 for a slope of 1. Let’s next look at the line which is P. This time we will count down 2 and over 2 so it will be negative 2 over 2 which will be negative 1, so they have opposite slopes. When you multiple these together (-1 and + 1) you will get a negative 1) so when you multiple two slopes together, and get negative 1 you know they are perpendicular, because the slope of perpendicular lines is the negative reciprocal. If the slope of one line is 1 over 1 you would flip it so it has a negative sign, and a slope of 1 over 1. Here is an overview of the different slopes. You have parallel which are two lines that never intercept, and you have perpendicular which have negative reciprocals so if you have a slope of ½ the perpendicular slope would be negative 2 because you flip it ( ½ becomes 2/1) and change the sign. Hope this was helpful.
What is a parallel line?
Parallel lines are two lines , that no matter how far they extend, do not intersect each other. They are the same distance apart at any given point.
The slope of parallel lines are equal.
What is a perpendicular line?
Perpendicular lines are two lines that intersect, and form right angles. Perpendicular lines have slopes that are negative reciprocals.