How many straight lines are used in the figure below? (A straight line cut into pieces by other lines is still one line.)
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 6
Each full straight line counts once, however many pieces other lines cut it into. In the figure below every line is numbered; group them by direction.
Horizontal lines (2): 1, 2
Slanting lines (4): 3, 4, 5, 6
Total \(=2+4=6\) straight lines.
Why the other options are incorrect
Option (1) 4 — Incorrect. This leaves out the 2 horizontal lines.
Option (3) 18 — Incorrect. This counts every piece between two corners or crossings as a separate line.
Option (4) 2 — Incorrect. This leaves out the 4 slanting lines.