Circle Theorems Calculator

Circle Theorems

  • Inscribed Angle = ½ × Central Angle
  • Angles in a semicircle = 90°
  • Opposite angles in cyclic quadrilateral = 180°
  • Tangent ⊥ Radius at point of contact
  • Equal chords = Equal angles from center

Note: These theorems are fundamental to circle geometry and are used extensively in geometric proofs and constructions. All angles are measured in degrees.