Ac is tangent to circle o at a. the diagram is not drawn to scale.
if mby =34 degrees, what is < yac?
a. 68 degrees
b. 51 degrees
c. 73 degrees
d. 56 degrees

Recall that a tangent to a circle is perpendicular to the diameter of the circle at the pont of tangency.

Given that AC is tangent to circle O at A, this means that line AB is a diameter of the circle.

Thus, angle BAC is a right angle.

Also, angle BAC = angle BAY + angle YAC.
i.e. 34 + <YAC = 90
<YAC = 90 - 34 = 56 degrees.