Given that the line AB is tangent with cicle ⊙O at point B, the radius r of ⊙O is 2. What is the area of the shaded area ?
1:OB=AC
2:BC=OB
Given that the line AB is tangent with cicle ⊙O at point B, the radius r of ⊙O is 2. What is the area of the shaded area ?
1:OB=AC
2:BC=OB