Which instrument is best for checking 90-degree and 45-degree angles as a general layout tool?

• A. Measuring Tape
• B. Circle Stencil
• C. Chalk Line
• D. Combination Square

Answer: (D)

Verifying and laying out angles with a reliable reference is essential for accurate work, and a tool that provides both a true corner and a built‑in 45-degree reference is ideal. The combination square fits this need best: its square head and sliding ruler give a precise 90-degree angle, so you can quickly check if an edge is truly square to another surface. It also includes a 45-degree orientation, allowing you to lay out or verify a 45-degree line by using the diagonal relation between the blade and head. This makes it a versatile general layout tool for both 90° and 45° angles. The other tools don’t provide both angle verification and transfer in one instrument: measuring tape measures length, a circle stencil is for arcs and circles, and a chalk line marks straight lines but doesn’t guarantee or transfer specific angles.