Question

Fan&Medal... Can someone check my answer please?

Triangle ABC has been rotated 90° to create triangle DEF. Using the image below, prove that perpendicular lines have opposite and reciprocal slopes. You must show all of your work to receive credit.

Answer 1

The slope of the perpendicular line is the negative reciprocal of the slope of the original line, and two lines with slopes that are negative reciprocals of each other are perpendicular to each other. The slope of BC should be the opposite reciprocal of EF. In order to figure out if it is the opposite reciprocal, you have to find the two slopes. The slope of BC is 4/3, and the slope of EF is -3/4. These two lines are perpendicular to each other, and the lines are opposite and reciprocal slopes.

Answer 2

@JoannaBlackwelder

Answer 3

That looks pretty good. :)

Answer 4

There is one thing I would add though.

Answer 5

Negative reciprocals always multiply together to give -1.

Answer 6

That was you can show mathematically that they are negative reciprocals by showing that the slopes multiply together to get -1.

Answer 7

ohhh, ok! Thank you so much! :D

Answer 8

No worries :)