Intersecting lines cross each other. Parallel lines never cross each other - they stay the same distance apart. You can use intersecting and parallel lines to work out the angles in a triangle.
What are intersecting lines?
Lines that cross each other
Lines that never meet each other
Lines that are the same length
What are parallel lines?
Straight lines that never meet each other
Which picture shows alternate angles?
Which picture shows opposite angles?
Which picture shows corresponding angles?
Which picture shows co-interior angles?
What's the size of angle ?