twilight is what it is called when day and night are equal length.
twilight is what it is called when day and night are equal length.
what is it called when day and night are equal length?
twilight
contemporary discussions of "prahara" often use 6:00 am (the time of sunrise at the equator and at the equinoxes) as a theoretical fixed point of reference for mapping out the "prahara"s at three-hour intervals (6-9, 9-12, etc.). this scheme is a useful pedagogical tool and an efficient way of applying the concept of "prahara" in a technological "clock" culture. however, it's important to realize that this rigid schema most likely does not capture the original application of "prahara." in a traditional, non-technological culture, the length of day and night are based on observable sunrise and sunset. the day, which starts at sunrise and ends at sunset, is divided into four "prahara"s of equal length; and, the night, which starts at sunset and ends at sunrise, is also divided into four equal watches. during the summer, when the days are longer than the nights, the "praharas" of the day will be longer than the "praharas" of the night, and vice versa during the winter.
prahar
a tangential quadrilateral is a kite if and only if any one of the following conditions is true:









































bullet::::- the area is one half the product of the diagonals.









































bullet::::- the diagonals are perpendicular. (thus the kites are exactly the quadrilaterals that are both tangential and orthodiagonal.)









































bullet::::- the two line segments connecting opposite points of tangency have equal length.









































bullet::::- one pair of opposite tangent lengths have equal length.









































bullet::::- the bimedians have equal length.









































bullet::::- the products of opposite sides are equal.
kite (geometry)