trig identities Flashcards
1
Q
sin(a+b)
A
sinacosb + cosasinb
2
Q
sin(a-b)
A
sinacosb - cosasinb
3
Q
cos(a+b)
A
cosacosb - sinasinb
4
Q
cos(a-b)
A
cosacosb + sinasinb
5
Q
tg(a+b)
A
tga+tgb/1-tga*tgb
6
Q
tg(a-b)
A
tga-tgb/1+tga*tgb
7
Q
ctg(a+b)
A
ctga*ctgb - 1/ctga+ctgb
8
Q
ctg(a-b)
A
ctga*ctgb + 1/ctga-ctgb
9
Q
sin2a
A
2sina*cosa
10
Q
cos2a
A
cos^2-sin^2
11
Q
tg2a
A
2*tga/1-tg^2a
12
Q
ctg2a
A
ctg^2-1/2*ctga
13
Q
cos a/2
A
+- sqrt(1+cosa/2)
14
Q
sin a/2
A
+- sqrt(1-cosa/2)
15
Q
tg a/2
A
+- sqrt(1-cosa/1+cosa)
16
Q
ctg a/2
A
+- sqrt(1+cosa/1-cosa)
17
Q
sina*cosb
A
1/2[sin(a+b)*sin(a-b)]
18
Q
cosa*sinb
A
1/2[sin(a+b)-sin(a-b)]
19
Q
cosa*cosb
A
1/2[cos(a+b)+cos(a-b)]
20
Q
sina*sinb
A
1/2[cos(a+b)-cos(a-b)]
21
Q
sina+sinb
A
2sin a+b/2 * cos a-b/2
22
Q
sina-sinb
A
2sin a-b/2 * cos a+b/2
23
Q
cosa+cosb
A
2cos a+b * cos a-b/2
24
Q
cosa-cosb
A
-2sin a+b/2 * sin a-b/2
