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BASIC TRIGONOMETRY REFERENCE
Trigonometric functions denote the relationship between the
subtended angle 'x' within a right-triangle and the ratio of
its sides:
/| sin(a) = y/r
r / | cos(a) = x/r
(hyp) / | y tan(a) = y/x
/ | (opp)
/a)__|
x (adj)
A triangle with hypotenuse (hyp) of unit-one length:
/|
/ | sin(a) = sin(a)/1
1 / | sin(a) cos(a) = cos(a)/1
/ | tan(a) = sin(a)/cos(a)
/a)__|
cos(a)
Via Pythagoras' theorem, sin^2(a)+cos^2(a) = 1.
USEFUL IDENTITIES:
sin(a) = cos(90 - a)
cos(a) = sin(90 - a)
1/sin(a) = csc(a)
1/cos(a) = sec(a)
1/tan(a) = cot(a)
sin(-a) = -sin(a)
csc(-a) = -csc(a)
cos(-a) = cos(a)
sec(-a) = sec(a)
tan(-a) = -tan(a)
cot(-a) = -cot(a)
sin(a -/+ b) = sin(a)*cos(b) -/+ cos(x)*sin(y) -- sign at right side is at left side
cos(a +/- b) = cos(x)*cos(b) -/+ sin(x)*sin(y) -- sign at left and right are opposite
tan(a) +/- tan(b)
tan(x +/- b) = -------------------
1 -/+ tan(a)*tan(b)