Angles in Parallel Lines

Angles in Parallel Linesvideo

Angles in parallel lines

What are parallel lines?

• Parallel lines are lines that are always equidistant (the same distance apart)

  • No matter how far the lines are extended in either direction, they will never meet

• Angles are formed when a straight line cuts through two parallel lines

What are corresponding angles in parallel lines?

• Find corresponding angles by looking for an F-shape

• Corresponding angles are equal

What are alternate angles in parallel lines?

• Find alternate angles by looking for a Z-shape

• Alternate angles are equal

What are co-interior (supplementary) angles in parallel lines?

• Find co-interior angles by looking for a C-shape

• Co-interior angles add up to 180°

How do I find missing angles in parallel lines?

• Look for shapes that look like F, Z, or C 

• Vertically opposite angles can also be used in problems involving parallel lines

  • The below diagram shows how identifying angle x, can lead to knowing information about several other angles

    • The green angle opposite is also x, as it is vertically opposite

    • The orange angle must be 180-x as angles on a straight line sum to 180°

• You should also be able to spot corresponding angles, alternate angles, and co-interior angles in this diagram