Which tool is a durable shop square featuring 90-degree and 45-degree markings and a scale for calculating rise and run?

• A. Speed Square
• B. 30-60 Degree Drafting Triangle
• C. Adjustable Speed Square
• D. Chalk Line

Answer: (A)

Recognizing a Speed Square and how its markings and built-in scale support quick right-angle work and rise/run calculations.

This tool is a durable shop square that sits flat on the workpiece and provides a true 90-degree edge. The 90-degree corner is used to square off lines or joints, while the 45-degree line offers a quick reference for common bevels and for splitting angles. The built-in scale lets you calculate rise and run, which is handy for laying out stairs, rafters, or any slope-based layout without extra measuring tools. Its sturdy construction ensures you can reuse it for repeated framing tasks with consistent accuracy.

Drafting triangles are designed for drawing angles and don’t include the rise/run scale used in carpentry layouts. A chalk line isn’t a square and isn’t used to mark right angles or calculate rise and run. An adjustable speed square is similar in function but the description here points to the standard fixed-speed square with 90 and 45 markings plus a rise/run scale.