The cafe wall optical illusion posted on Twitter challenges people to figure out if the lines are straight or bend at an angle. A myriad of optical illusions keeps us glued to our screens as we keep ...

Horizontal lines run left to right, parallel to the horizon, with slope 0 and equation y = k. Vertical lines run top to bottom, perpendicular to the horizon, with undefined slope and equation x = k.

An angle is the space between two lines that start at the same point. This point is called the vertex. Angles measure the size of a turn in degrees. You can show degrees using the symbol ° after the ...