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 parallelograms, such as rectangles and squares, contain right angles. Another type of parallelogram, known as a rhombus, may or may not contain right angles. Quadrilaterals are closed, co-planar geometric shapes that comprise two diagonals and four sides, where all four interior angles have a sum of 360 degrees. Special types of quadrilaterals include parallelograms, rectangles, squares, rhombuses, trapezoids and kites. Parallelograms contain two pairs of opposing sides that are parallel and equally long. The opposite angles of parallelograms are also equal. Rectangles, squares and rhombuses are considered parallelograms because they share the same properties as a parallelogram. The four interior angles of rectangles and squares are all right angles, or 90-degree angles. The opposite angles, also called supplementary angles, have a sum of 180 degrees.