s.html Year 8 Mathematics Parallel Lines

Learning Intentions – Understand that parallel lines are always the same distance apart – Understand the term transversal – Recognise Corresponding, Alternate and Interior angles – Use the letters F, Z and U to aid recall of facts – Be able to use angles associated with parallel lines in problems

Parallel Lines Lines are said to be parallel if they are always the same distance apart Arrows are used to identify parallel lines A line crossing parallel lines is called a transversal

Examples

Vertically Opposite Angles Angles in the opposite corners when two lines cross are called Vertically Opposite angles Vertically Opposite angles are equal We can find Vertically Opposite angles by looking for the letter X. OX

Corresponding Angles Angles in matching corners of parallel lines and transversals are called Corresponding angles Corresponding angles are equal We can find Corresponding angles by looking for the letter F Fat Cat

Corresponding Angles Link the Corresponding angles a b e h g d f c

Alternate Angles The pairs of angles on opposite sides of the transversal but inside the two lines are called Alternate angles. Alternate angles are equal We can find Alternate angles by looking for the letter Z ZebrA

Alternate Angles Link the pairs of Alternate angles a b e h g d f c

Interior Angles When parallel lines are cut by a transversal the angles inside the parallel lines are called Interior angles Pairs of Interior angles add to 180 o We can find Interior angles by looking for U, C or n UnICorn

Interior Angles Link the pairs of Interior angles a b e h g d f c

Questions

Giving Reasons Find the sizes of the unknown angles, giving reasons for your answers Angle x = 105 o (corresponding angles) Angle y = 55 o (alternate angles) Angle z = 125 o (Interior angles)