Question

in the fig angle aob chord subtends equal angle to 60° at the centre of the circle if oa =5cm find ab

Answer 1

ab is also equal to 5cm
since oa=ob angleA =angle B they are equal to 60 degree hence it is an equilateral triangle. Therefore all sides are equal

Answer 2

In the figure,
OA = OB ( they are the radii)
So , OAB is a isosceles triangle
We know two angles are same in an isosceles triangle
So oab = oba
By angle sum property ,
Oab + oba + aob = 180
2(oab)=180-60
Oab = 60
Here all angles are equal. So it is an equilateral triangle
In equilateral triangle all sides are equal
So ab = 5cm