Warm Up

• Write the equation of a line that passes through the points (1, -11) and (5, -7). Then find the line parallel to it that passes through the point (10, 3).

• Find the angle measures of the five angles. Be careful, it’s not as easy at it looks.

A B

C D

155°

∠165°

65°40° 115°∠2

∠3∠4

∠5

GeometryPerpendicular Lines

Learning Outcomes

• I will be able to write the equation of a line that is perpendicular to another line and goes through a given point!

Activity

What does this mean?

• In order for two lines to be perpendicular their slopes must be the opposite reciprocal of each other.

• For example, if we have the line y = 3x + 1, then a line perpendicular to this line might be y = - x + 1.

What does this mean?

• How can we find a line perpendicular to y = 2x + 1?

• What if we wanted to find a line perpendicular to y = 2x +1 but through the point (3, 4)?

Let’s put this all together!

• Find the slopes of both lines, then determine if they are perpendicular.

Are these lines perpendicular?

• Set I

• Set II

Challenge Problem

• Find a line perpendicular to the line on the left through the point P.

VOCAB QUIZ NEXT CLASS!

Exit Ticket

• Pg. 175: 10-16, 21-36, 38-41, 47-50, 55-62

Homework