Question

16. AB is a tangent drawn from a point A to a circle with centre O and BOC is a
diameter of the circle such that ZAOC =110°. Find ZOAB.
​

Answer 1

The answer is 20°

In Diameter Line BOC, Angle AOC + Angle AOB = 180°

Therefore, Angle AOB = 180° - 110° = 70°

It is property of a Circle that it makes 90° angle from the center on every tangent.

So, Angle OBA = 90°

Now,

Using the Sum of Angles of a Triangle = 180°,

Angle OAB + Angle AOB + Angle ABO = 180°

Therefore, Angle OAB = 20°