GEO003 · Geometry basics · Classes 3–12
Angle
An angle is formed by two rays with a common end point (the vertex). It is measured in degrees.
Angle📐 Formula
Acute < 90° = right < obtuse < 180° = straight < reflex < 360°; complement = 90° − θ, supplement = 180° − θ
✏️ Worked example
θ = 50° is acute; complement 40°, supplement 130°.
🌍 Where it is used
Clock hands, ramps, door openings and roof slopes.
❓ Quick check
What is the supplement of 70°?