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.
No. A quadrilateral is simply a 4 sided polygon. There are 2 special subsets of polygons. The first is a trapezoid, which has 1 pair of opposite sides being parallel. If the other two pairs of base angles and opposite sides are congruent, then the trapezoid is isosceles. The four sides in a trapezoid are NEVER congruent. The other special subset of quadrilaterals is parallelograms. A parallelogram has opposite sides being both congruent and parallel. Opposite angles are also congruent and consecutive angles are supplementary (= 180). Subsets of parallelograms are rectangles, where all the angles are right angles (=90) and rhombuses, which DO have all 4 sides being congruent. A special quadrilateral that is BOTH a rhombus and a rectangle is the square. In short, only squares and rhombuses have 4 congruent sides. The rest do not.