The avian cardiovascular system is able to quickly respond to changes in levels of activity (e.g., resting vs. flying) via changes in heart rate, cardiac output, & blood flow (by vasocontriction and vasodilation of vessels).
A square is a quadrilateral with all right angles and all equal sides. A square is also a parallelogram, a rectangle, and a rhombus and has all the properties of all these special quadrilaterals. Figure 3 shows a square. Figure 3 A square has four right angles and four equal sides. Figure 4 summarizes the relationships of these quadrilaterals to one another.
Some regard only quadrilaterals with one single pair of parallel sides as trapezoids. Others regard the parallelogram, with two pairs of parallel sides, as a special type of trapezoid. This definition includes rectangles, rhombuses and squares as trapezoids as well because they are all special types of parallelogram.