Q.In a circle of diameter 40 cm, the length of a chord is 20 cm. Find the length of minor arc of the chord.

Step 1: Diameter $=40$ cm $\Rightarrow r=20$ cm. Chord $=20$ cm.

Step 2: $\text{chord}=2r\sin\left(\frac{\theta}{2}\right) \Rightarrow 20=2(20)\sin\left(\frac{\theta}{2}\right) \Rightarrow \sin\left(\frac{\theta}{2}\right)=0.5 \Rightarrow \frac{\theta}{2}=30° \Rightarrow \theta=60°=\frac{\pi}{3}$ radian. …

Use the chord-length formula chord = 2r sin(θ/2) to find the cent …

• Using the diameter (40 cm) instead of the radius (20 cm) in the chord-length formula. …