Two lines are parallel if and only if they lie in the same plane and do not intersect. Parallel lines never cross. Parallel lines are always the same distance apart, which is referred to as being “equidistant”. For our purposes, parallel lines will always be straight lines that go on indefinitely.

Consequently, why do parallel lines meet at infinity?

In projective geometry, any pair of lines always intersects at some point, but parallel lines do not intersect in the real plane. The line at infinity is added to the real plane. This completes the plane, because now parallel lines intersect at a point which lies on the line at infinity.

## What is the proper name for Z angles?

Alternate angles form a ‘Z’ shape and are sometimes called ‘Z angles’. a and b are adjacent angles. Adjacent angles add up to 180 degrees. (d and c, c and a, d and b, f and e, e and g, h and g, h and f are also adjacent).

## What shape is parallel?

The trapezoid has one pair of parallel sides. The parallelogram, rectangle, and square all have two pairs of parallel sides. Other less common shapes with parallel sides include any of the ‘-gons’ with an even number of sides, such as a hexagon, octagon, decagon, etc.