No, it cannot - unless it was a rectangle to start with.
Yes, they will be the same size and shape as each other.
If the heights and bases are the same, then the triangle is half the area of the parallelogram.
a circle
That would depend on the dimension of the green triage. If the triangle was formed by joining two opposite corners of the parallelogram then it would be half the area of the parallelogram. Area of parallelogram = 15*2 = 30 square cm. 1/2 the area = 15 square cm.
a smaller cylinder when cut horizontally. A semi-circle when cut vertically
Yes.
Yes.
Yes.
Yes.
Yes cutting a rectangle in half (either horizontally or vertically) will yield two smaller rectangles (each of which is the same size and shape as the other).
Yes.
no
Yes
Yes
Yes.
Yes, you can cut a rectangle any way you please.
They make two congruent rectangles, not to rectangles! This is because the line joining the midpoints of opposite sides are lines of [reflective] symmetry.