Question

chord AB subtends angle AOB= 60° at the centre of a circle. if OA =5cm ,find the length of AB.

Answer 1

here
angle b/w chords=60
radius=5cm
AB= 2pie R *ANGLE/ 360
AB=2*22/7*5/6
AB= 5.2cm

Answer 2

The length of AB is 5cm

Step-by-step explanation:

• In triangle OAB , angle AOB= 60°

• side OA = side OB. (radii of same circle)
• angle ∠OAB = angle ∠OBA = x.  

• Angle ∠OAB+angle ∠OBA+ angle AOB=180°.

                 x+x+60° = 180°.

              =  2x=180°-60°.

                x=120°/2 = 60°.

Thus, triangle ABC is an equilateral triangle,

therefore , AB = OA.

hence, AB = 5 cm.

the length of AB is 5cm