From the diagram above. ABC is a triangle inscribed in a circle center O. ∠ACB = 40^o and |AB| = x cm. calculate the radius of the circle.

• A.\(\frac{x}{sin 40^o}\)
• B.\(\frac{x}{cos 40^o}\)
• C.\(\frac{x}{2 sin 40^o}\)
• D.\(\frac{x}{2 cos 40^o}\)