Question

Directions: How many minimum number of straight lines are required to draw the problem figure ?

• A. 18
• B. 19
• C. 20
• D. 21

Hint:

Count every maximal straight line of the figure once: a line that runs unbroken through several junctions is a single line, but two collinear pieces separated by a gap are two lines.

Answer 1

The Correct Option is B

Group the straight lines of the figure by direction.
Vertical lines (4): the left edge of the central rectangle (one line from top to bottom), the right edge of the central rectangle (one line from top to bottom), the short middle vertical in the top box (it stops where it meets the slanting line) and the long middle vertical that starts at the first horizontal line below it and runs down to the bottom (the two middle pieces are separated by a gap, so they are different lines).
Horizontal lines (5): the top edge, the line through the upper corners of the two side figures, the long central line through the middle (touching the tips of both side figures), the line through the lower corners of the side figures, and the bottom edge.
Inclined lines (10): one slanting line in the top box, one slanting line in the bottom box, and four slanting lines in each of the two side figures (left and right), because every side figure is made of two outer slanted sides and two inner slanted lines meeting at the central line: 2 + 4 + 4 = 10.
Total = 4 + 5 + 10 = 19.
Answer: (2) 19