Solve the following problems in geometry:
In the circle with radius 
we draw a rectangle whose sides are in the ratio 
. Calculate the perimeter of the rectangle. What percentage of the area of the circle is the area of the rectangle?
In a rhombus, the difference of diagonals is 
, and its area measures 
. Calculate the lengths of the diagonals and its side. Leave the result in surd form.
The sides of the triangle represent the first three terms of an arithmetic sequence with a difference of 4. The plane of the triangle is 
. Calculate the lengths of the sides.
