What is the value of a?
answer options: 27.5, 90, 45, 50

90°

Step-by-step explanation:

Arc a subtends and angle of 45° to the circumference of the circle

We know that;

An angle subtended by an arc to the center of a circle is twice the angle subtended by the same chord to the center of the circle.

Therefore, if arc a subtends and angle of 45° to the circumference of the circle then;

a will be = 45 × 2

              =  90°