Algebra 1 : How to find the equation of a perpendicular line

Study concepts, example questions & explanations for Algebra 1

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Example Questions

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Example Question #91 : Perpendicular Lines

Which of the following lines is perpendicular to the following line?

Possible Answers:

Correct answer:


Perpendicular lines have slopes that are opposite reciprocals meaning that the slope is flpped. The equation that satisfies both of these criteria is:

Example Question #92 : Perpendicular Lines

Suppose a line has an x-intercept of one and a y-intercept of two. What is the equation of the perpendicular line which pass through the point ?

Possible Answers:

Correct answer:


Write the points that correspond to the x and y-intercepts given in the problem.

X-intercept of one: 

Y-intercept of two: 

Find the slope of this line connected with these points.

The slope is negative two. The slope of the perpendicular line is the negative reciprocal of this slope.

Write the slope-intercept form.

Substitute the perpendicular slope with the point that this line will pass through.

Solve for the y-intercept, .

Subtract nine halves on both sides.

Simplify both sides.

With the perpendicular slope and the y-intercept, write the equation of the line.

The answer is:

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