\line(x-slope,y-slope){length}
The \line command draws a line of the specified length and slope.
The slope is determined by (x-slope,y-slope) which are signed integers of magnitude less than or equal to 6 and which have no common divisor except for plus or minus one; For example (1,0) is a horizontal line; (1,1) gives a slope of 45 degress; (0,1) is a vertical line; (-1,1) is 135 degrees.
The horizontal extent of the line is given by the length parameter, except in the case of a vertical line in which case length specifies the vertical height.