including vertical, horizontal, parallel and perpendicular. What are parallel and perpendicular lines? Discover the difference between parallel and perpendicular lines. Measuring angles Find out ...

How many did you find? You can see that there are 4 vertical pencils and 4 horizontal ... Perpendicular lines cross at right angles. That's why they're not used in running races.

However, viewing angles differ between LCD and front and rear-projection screens. Horizontal and vertical angles are often not the same. For example, looking down on a screen may have less of a ...