Trig Identities Flashcards
1
Q
sin (u+- v)
A
sinucosv +- cosusinv
2
Q
cos (u +- v)
A
cosucosv-+ sinusinv
3
Q
tan (u += v)
A
(tanu +- tanv)/(1 -+ tanutanv)
4
Q
sin2u
A
2sinucosu
5
Q
cos2u
A
cos^2u - sin^2u = 2cos^2u - 1 = 1- 2sin^2u
6
Q
tan2u
A
2tanu/(1-tan^2u)
7
Q
Law of Sines:
A
a/sinA = b/sinB = c/sinC
8
Q
When to use Law of Sines:
A
AAS, ASA
9
Q
Area of an Oblique Triangle:
A
Area = .5bcsinA = .5absinC = .5acsinB
10
Q
Law of Cosines:
A
a^2 = b^2 + c^2 - 2bccosA (this can be for b^2 and c^2 as well)
11
Q
When to use Law of Cosines:
A
SSS, SAS
