Question

Is equal to an arc of circle and two times the angle subtended by it at the vertex​

Answer 1

both the angle are equal to each other.

Answer 2

Answer:

Theorem: The angle subtended by an arc of a circle at its center is twice of the angle it subtends anywhere on the circle's circumference. The proof of this theorem is quite simple, and uses the exterior angle theorem – an exterior angle of a triangle is equal to the sum of the opposite interior angles.