一、Fill in the Blanks (10 points each, total 80 points)
1. Given $A B$ is the diameter of $\odot O$, $A B=1$, extend $A B$ to point $C$, such that $B C=1$, $C D$ is the tangent of $\odot O$, $D$ is the point of tangency. Then the area of $\triangle A B D$ is $\qquad$