TRIG. IDENTITIES Flashcards
1
Q
sin (a + b)
A
sin a cos b + cos a sin b
2
Q
cos (a + b)
A
cos a cos b - sin a sin b
3
Q
sin (a - b)
A
sin a cos b - cos a sin b
4
Q
cos (a - b)
A
cos a cos b + sin a sin b
5
Q
sin^2 x + cos^2 x
A
1 (Pythagorean identity)
6
Q
1 + tan^2 x = sec^2 x
A
sec^2 x (Pythagorean identity)
7
Q
1 + cot^2 x = csc^2 x
A
csc^2 x (Pythagorean identity)
8
Q
reciprocal of sin x is?
A
1/csc x
9
Q
reciprocal of cos x is?
A
1/sec x
10
Q
reciprocal of tan x is?
A
1/cot x
11
Q
reciprocal of csc x is?
A
1/sin x
12
Q
reciprocal of sec x is?
A
1/cos x
13
Q
reciprocal of cot x is?
A
t/tan x
14
Q
tan x = x/y?
A
sin x/cos x (Quotient identity)
15
Q
tan 2x = ?
A
2tanx / 1-tan^2x
16
Q
tan(a+b) = ?
A
(tan a + tan b)/1- tan a(tan b)
17
Q
tan(a-b) = ?
A
(tan a - tan b)/1 + tan a(tan b)
18
Q
sin 2x = ?
A
2 sin x cos x
19
Q
cos 2x = ?
A
cos^2 x - sin^2 x
2cos^2 x - 1
1 - 2sin^2 x
20
Q
tan 2x = ?
A
2 tan x/(1-tan^2 x)
21
Q
A
