Trig Identify Flashcards
Pythagorean trig identities
sin^2(x) + cos^2(x) =1
sec^2(x) - tan^2(x) =1
csc^2(x) - cot^2(x) =1
sin(-x)
-sinx
cos(-x)
cosx
tan(-x)
-tanx
Law of cosine
(c^2) = (a^2) + (b^2) - (2ab)cos(c)
Half angle: sin(x/2)
+/- √((1-cosx)/2)
Half angle: cos(x/2)
+/- √((1+cosx)/2)
Half angle: tan(x/2)
(1-cosx)/sinx
sin2x
2sinxcosx
cos2x
cos^2(x) - sin^2(x)
2cos^2(x) - 1
1 - 2sin^2(x)
tan2x
2tanx / (1- tan^2(x))
lim x->0 using sin/cos
((sinx + 1) / x ) = 1
((1 - cosx) / x ) = 0
30° in radians
π/6
60° in radians
π/3
60° in radians
π/3
45° in radians
π/4
sin(x) quadrants that are +
1&2
cos(x) quadrants that are +
1 & 4
tan(x) quadrants that are +
1 & 3
Right triangle ratios
45° A:1 B:1 C:√2
a:30° b:60° A:1 B:√3 C:2
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)
Law of sines
a/sinA = b/sinB = c/sinC
Area of a oblique triangle
(1/2)sinA(bc)
