China Naming Network - Feng Shui knowledge< - Points C and D are on a circle O with a diameter of AB, and CD bisects ∠ACB. If AB = 2, ∠ CBA = 15, what is the length of the CD?
Points C and D are on a circle O with a diameter of AB, and CD bisects ∠ACB. If AB = 2, ∠ CBA = 15, what is the length of the CD?
Add OC, OC=OB.
So ∠ OBC = ∠ OCB = 15.
Because AB is the diameter, ACB = 90.
Because the CD score is ∠ACB, ∠ BCD = 45.
∠OCD=∠BCD-∠OCB=45 - 15 =30
AB=2,r= 1,OC= 1
So CD=√3