Trig Identities Flashcards
sin²(x)
1 - cos²(x)
1/2[1 - cos(2x)]
cos²(x)
1 - sin²(x)
1/2[1 + cos(2x)]
sec²(x)
1 + tan²(x)
tan²(x)
sec²(x) - 1
1 - cos(2x))/(1 + cos(2x)
csc²(x)
1 + cot²(x)
cot²(x)
csc²(x) - 1
Pythagorean Identities
sin²(x) + cos²(x) = 1
1 + tan²(x) = sec²(x)
1 + cot²(x) = csc²(x)
sin(π/2 - x)
cos(x)
csc(π/2 - x)
sec(x)
sec(π/2 - x)
csc(x)
cos(π/2 - x)
sin(x)
tan(π/2 - x)
cot(x)
cot(π/2 - x)
tan(x)
Cofunction Identities
sin(π/2 - x) = cos(x) cos(π/2 - x) = sin(x) tan(π/2 - x) = cot(x) csc(π/2 - x) = sec(x) sec(π/2 - x) = csc(x) cot(π/2 - x) = tan(x)
sin(a + b)
sin(a)cos(b) + sin(b)cos(a)
sin(a - b)
sin(a)cos(b) - sin(b)cos(a)
cos(a + b)
cos(a)cos(b) - sin(a)sin(b)
cos(a - b)
cos(a)cos(b) + sin(a)sin(b)
tan(a + b)
(tan(a) + tan(b))/(1 - tan(a)tan(b))
tan(a - b)
(tan(a) - tan(b))/(1 + tan(a)tan(b))
Sum and Difference Formulas
sin(a + b) = sin(a)cos(b) + sin(b)cos(a)
sin(a - b) = sin(a)cos(b) - sin(b)cos(a)
cos(a + b) = cos(a)cos(b) - sin(a)sin(b)
cos(a - b) = cos(a)cos(b) + sin(a)sin(b)
tan(a + b) = (tan(a) + tan(b))/(1 - tan(a)tan(b))
tan(a - b) = (tan(a) - tan(b))/(1 + tan(a)tan(b))
sin(2x)
2sin(x)cos(x)
cos(2x)
cos²(x) - sin²(x)
2cos²(x) - 1
1 - 2sin²(x)