trig identities Flashcards
1
Q
law of cosines
A
a^2=b^2+c^2-2bcCosA
b^2=a^2+c^2-2acCosB
c^2=a^2+b^2-2abCosC
2
Q
law of sines
A
SinA/a=SinB/b=SinC/c
3
Q
tan u/2
A
1-cosu/sinu
4
Q
cos u/2
A
+- square root of 1+cosu/2
5
Q
sin u/2
A
+- square root of 1-cosu/2
6
Q
tan2x
A
2tanx/1-tan^2x
7
Q
cos2x
A
cos^2x-sin^2x
8
Q
sin2x
A
2sinxcosx
9
Q
tan(s+t)
tan(s-t)
A
tans+tant/1-tanstant
tans-tant/1+tanstant
10
Q
cos(s+t)
cos(s-t)
A
cos(s)cos(t)-sin(s)sin(t)
cos(s)cos(t)+sin(s)sin(t)
11
Q
sin(s+t)
sin(s-t)
A
sin(s)cos(t)+cos(s)sint(t)
sin(s)cos(t)-cos(s)sin(t)
12
Q
sin^2x+cos^2x
A
1
13
Q
sin^2x
A
1-cos2x/2
14
Q
cos^2x
A
1+cos2x/2
15
Q
tan^2x
A
1-cos2x/1+cos2x
