Euclid was the one to construct the golden rectangle
2 circles and a rectangle
Draw any square or rectangle, and you have it.
Sure. It's called a "square"; you can consider the square a special case of a rectangle.
If you assume that 2.5 refers to the scale factor, you multiply each linear measurement by 2.5. This includes the width, the length, and - if you want to use it to construct your new rectangle - the diagonals. It also happens to include the perimeter, but you probably won't need that to construct the rectangle.
Construct the rectangle that contains the right angle subtended by the vectors. Calculate or construct the diagonal of the rectangle. The diagonal is the hypotenuse of a right triangle with the two vectors as sides. The hypotenuse is also the vector that is the sum of the two original vectors. Calculate the magnitude of that vector by applying the theorem.
Divide one edge into five equal parts and construct lines perpendicular to that edge at those points.
Its beacause that's how all rectangles are if is not at or higher than 90 degress than its a rectangle To construct 90 degrees in the centre of a rectangle, connect the midpoints of each set of parallel lines. You will then have a cross in the centre that is perpendicular to each other (90 degrees).
Most building and joinery materials are inherently rectagular as manufactured. Thus this shape is the simplest to construct. Tables that are circles or elipses result in material wasted.
Circles and rectangles are plane (2-dimensional) figures, so it doesn't seem that they can be used to construct solids.