Rectangle moves and overlaps triangle

A rectangle departs from the position in a figure and is moving in the direction of an arrow at 2 cm/s.

Answer

(1) Find the time when the rectangle is completely inside of the triangle.

(2) Find the area of the portion of the rectangle out of a triangle 12 seconds after leaving.

(3) Find the time when the area of the portion of the rectangle which is contained in the triangle is 30 cm² or more.