CIR007 · Circles · Classes 9–10
Inscribed angles
An inscribed angle has its vertex on the circle. It is half the central angle on the same arc, so it stays the same wherever P moves on the arc.
θ = ½ centralInscribed angles
📐 Formula
inscribed angle = ½ × central angle
✏️ Worked example
Central angle 70°: every inscribed angle APB = 35°. Move P: the angle does not change.
🌍 Where it is used
Finding angles in circular designs; best seat to view a screen.
❓ Quick check
Angle in a semicircle is…
🏋️ Practice
EasyCentral angle 100°. Inscribed angle?
Answer: 50°
MediumInscribed angle 25°. Central angle?
Answer: 50°
ChallengeTwo inscribed angles on the same arc are…?
Answer: Equal