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Visits since  Oct 2002

sin(-x) = -sin(x)
csc(-x) = -csc(x)
cos(-x) = cos(x)
sec(-x) = sec(x)
tan(-x) = -tan(x)
cot(-x) = -cot(x)

sin^2(x) + cos^2(x) = 1	tan^2(x) + 1 = sec^2(x)	cot^2(x) + 1 = csc^2(x)
sin(x y) = sin x cos y cos x sin y
cos(x y) = cos x cosy sin x sin y

tan(x y) = (tan x tan y) / (1 tan x tan y)

sin(2x) = 2 sin x cos x

cos(2x) = cos^{^2}(x) - sin^{^2}(x) = 2 cos^{^2}(x) - 1 = 1 - 2 sin^{^2}(x)

tan(2x) = 2 tan(x) / (1 - tan^{^2}(x))

sin^{^2}(x) = 1/2 - 1/2 cos(2x)

cos^{^2}(x) = 1/2 + 1/2 cos(2x)

sin x - sin y = 2 sin( (x - y)/2 ) cos( (x + y)/2 )

cos x - cos y = -2 sin( (x-y)/2 ) sin( (x + y)/2 )

Given Triangle abc, with angles A,B,C; a is opposite to A, b oppositite B, c opposite C:

a/sin(A) = b/sin(B) = c/sin(C) (Law of Sines)

(a - b)/(a + b) = tan 1/2(A-B) / tan 1/2(A+B) (Law of Tangents)

( Tables used with permission from David J. Manura  )