Which drafting tool is used to render straight lines perpendicular to a reference surface?

• A. Ruler
• B. T-square
• C. Level
• D. Protractor

Answer: (B)

To render straight lines perpendicular to a reference surface, you need a guide that fixes a right-angle relationship to that surface. The T-square provides this: its blade sits flat against the drawing board edge, and the head is at a 90-degree angle to the blade. That built-in perpendicular relationship gives you a reliable reference for lines that are truly perpendicular to the surface as you draw. A ruler is just a straight edge with no enforced angle, a level shows horizontal/vertical orientation but isn’t used to draw perpendicular lines, and a protractor measures angles but doesn’t provide a perpendicular drafting guide.