It is known that, as shown in the figure, CD is the tangent of ⊙ o, C is the tangent point, and the extension line of diameter AB intersects CD at D, connecting OC and BC. (1) write three different types of conclusions; (2) if BD = ob, prove: CA = CD

It is known that, as shown in the figure, CD is the tangent of ⊙ o, C is the tangent point, and the extension line of diameter AB intersects CD at D, connecting OC and BC. (1) write three different types of conclusions; (2) if BD = ob, prove: CA = CD

(1) Different types of conclusions are as follows: △ BCD ∽ CAD, OC ⊥ CD, △ ABC is a right triangle, oc2 + CD2 = OD2, CD2 = DB · Da, ∠ ECD = ∠ OCA; (2) it is proved that: ∵ CD is the tangent of circle O, ≁ OC ⊥ CD, ≁ ob = BD, ≁ BC is the middle line on the hypotenuse of right triangle OCD, ≁ BD = ob = BC = OC, ≁