Right Angles – Exactly 90 Degrees

A right angle measures exactly 90° – a quarter of a full turn. It's the angle you see at the corner of a square or rectangle, and it's so fundamental to geometry that it gets its own special diagram symbol: a small square drawn inside the angle's corner, instead of a curved arc.

The name comes from the Latin angulus rectus, meaning “upright angle” – the Romans used the term for the perfectly upright corner formed where a vertical wall meets level, horizontal ground.

Recognising a Right Angle

Real-Life Application

• Buildings: most walls, doors, and windows are built at right angles for stability.
• Furniture: table and shelf corners are right angles by design.
• Set squares: drafting tools include a fixed 90° corner for precise drawing.

Key Takeaways

Practice: Right Angles