Arccos(cos 7pi/2)
cos 7pi/2 = cos 630 = cos (630-360) = cos 270 = 0
arccos(0) = 90 since cos 90 = cos 270
(x): 0 - 30 - 45 - 60 - 90
sin (x) 0 - 1/2 - 1/2 √3 - 1/2 √3 - 1
cos (x) 1 - 1/2 √3 - 1/2 √3 - 1/2 - 0
tan (x) 0 - 1/√3 - 1 - √3 - ∞
Rules for sin cos tan value in each quadrant :
quadrant = I(0-90) - II (90-180)- III(180-270) - IV(270-360)
sin (x) = positive- positive - negative - negative
cos (x) = positive- negative- negative - positive
tan (x) = positive- negative- positive - negative
