(6) Csc of Angle XAB:
csc XAB = -csc X1AB = -csc (XAB - 180)
Figure 4-14. Angles between 180 and 270
i. The functions of any angle between 270 and 360€ may be expressed as the function of the
acute angle, which is found by subtracting the given angle from 360€. Assuming that angle XAB in
Figure 4-15, page 22, can have any value from 270€ to 360€, you can derive the following formulas for
the functions of any angle in the fourth quadrant.
(1) Sin of angle XAB:
sin XAB = -sin (360 - XAB)
(2) Cos of angle XAB:
cos XAB = cos (360 - XAB)
(3) Tan of angle XAB:
tan XAB = -tan (360€ - XAB)
(4) Cot of angle XAB:
cot XAB = -cot (360€ - XAB)
(5) Sec of angle XAB:
sec XAB = sec (360 - XAB)
(6) Csc of angle XAB:
csc XAB = -csc (360€ - XAB)
4-21
EN0591
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