Writing Equations of Parallel and Perpendicular Lines: Practice

This video continues with writing equations of parallel and perpendicular lines by looking at two more example problems from the Khan Academy exercise linked below.

The general strategy is to first determine what the slope of the line should be and then use either slope intercept form of point slope form to determine the y intercept of the line.

Parallel lines have the same slope and when written in slope intercept form, usually only have different y intercepts. Perpendicular lines have slopes that are negative reciprocals of each other and also different y intercepts when written in slope intercept form. In other words, the slope of one line is written as a fraction, flipped over, and made negative to equal the slope of the other line. Another way to look at it is that the product of the slopes of perpendicular lines is equal to negative 1.

Khan Academy exercise to practice: