The third question (18) is a minor one with the following topics.

As shown in the figure, in a quadrangular pyramid S-ABCD with a right-angled trapezoid bottom, < ABC = < bad = 90 degrees, the bottom of SA is perpendicular to ABCD, SA = AB = BC = 1, and AD = 1/2.

(1) Find the volume of the pyramid S-ABCD (2) Find the tangent of the angle formed by ABCD at the bottom of SC.