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