Question

What is the measure of OAC

Answer 1

27°

Explanation:

• A tangent meets a radius at 90°

• Angles in a trainable sum to 180°
• 180 - 90 - 63 = 27°

Answer 2

∠OAC = 27°

Explanation:

The radius of the circle is perpendicular to the tangent line.

Therefore, ∠ACO = 90°

The interior angles of a triangle sum to 180°

⇒ ∠OAC + ∠ACO ∠ COA = 180°

⇒ ∠OAC + 90° + 63° = 180°

⇒ ∠OAC + 153° = 180°

⇒ ∠OAC = 180° - 153°

⇒ ∠OAC = 27°