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## Geometry (all content)

### Course: Geometry (all content)>Unit 1

Lesson 3: Parallel and perpendicular

# Parallel and perpendicular lines review

Review the basics of parallel and perpendicular lines.  Identify and draw parallel and perpendicular lines in some practice problems.

## What are $\greenD{\text{perpendicular lines}}$start color #1fab54, start text, p, e, r, p, e, n, d, i, c, u, l, a, r, space, l, i, n, e, s, end text, end color #1fab54 and $\purpleD{\text{parallel lines}}$start color #7854ab, start text, p, a, r, a, l, l, e, l, space, l, i, n, e, s, end text, end color #7854ab?

start color #1fab54, start text, P, e, r, p, e, n, d, i, c, u, l, a, r, space, l, i, n, e, s, end text, end color #1fab54 are lines that meet at right angles.
Two lines that meet at right angles.
start color #7854ab, start text, P, a, r, a, l, l, e, l, space, l, i, n, e, s, end text, end color #7854ab are always the same distance apart from each other — no matter how far they are extended, they will never meet.
Two lines that will never cross.

## Practice set 1: Identify parallel and perpendicular lines

Problem 1A
• Current
Which of the following pairs of sides in triangle, G, A, Z are perpendicular?
A triangle GAZ. The angle at Z has a box at its vertex connecting lines AZ and GZ. The angles at G and A are acute angles.

Want to try more problems like this? Check out this exercise.

## Practice set 2: Draw parallel and perpendicular lines

Problem 2A
• Current
Any pair of points can be connected by a line.
Use the green line to connect the pair of black points that makes a line parallel to the blue line segment.

Want to try more problems like this? Check out this exercise.

## Want to join the conversation?

• Quick question how do you prove that lines are parallel? I can't seem to find that on here and i really need to know!
• If you draw a line through the 2 lines, it should be perpendicular to both lines.
• I am having trouble remember these. Anyone have any tips to help me remember?

Edit : Case Closed. But thank you Taylyn for answering my question! Everyone have a nice day.
• Yes. In the word Parallel, the double L's are side by side, and if going on in a straight line, would never touch. So, the double L's in Parallel are, well, parallel. Use those as an example to help you remember what parallel means.
• Are perpendicular any kind of lines that intersect each other? I've got to know this!
• Yes, perpendicular lines intersect each other with 4 90-degree angles.
• Does a perpendicular line ALWAYS have to be 90 degrees? Just a Question
• Yes, a perpendicular line must always be at a 90-degree angle
• does perpendicular line have to be the exactly 90 degrees?
• It always have to be exactly at a right angle, and a right angle is always 90 degrees so yes.
• What happens if a Parallel line goes through a regular line so that make it perpendicular so what is that.
• If the parallel line goes through the line, the lines will not be parallel anymore, so they will only be perpendicular if they meet at a right angle.
• Why does the human brain have to know what geometry is?