Trigonometry Flashcards
basic formulae & identities. target time per round: 30 sec
1
Q
sin(−θ)
A
−sin θ
2
Q
cos2A
A
cos2A–sin2A = 1–2sin2A = 2cos2A-1 = [(1-tan2A)/(1+tan2A)]
3
Q
sin x – sin y
A
2 cos [(x+y)/2] sin [(x-y)/2]
4
Q
cos(π/2-A)
A
sin A
5
Q
sin(2π-A)
A
-sin A
6
Q
sin(2π-A)
A
-sin A
7
Q
sin x + sin y
A
= 2 sin [(x+y)/2] cos [(x-y)/2]
8
Q
sin(π+A)
A
-sin A
9
Q
cot(A-B)
A
= [(cot A cot B + 1)/(cot B – cot A)]
10
Q
cos3A =
A
4cos3A – 3cosA
11
Q
sin3A =
A
3sinA – 4sin3A
12
Q
sin2A
A
2sinAcosA = [2tan A /(1+tan2A)]
13
Q
cos x – cos y
A
-2 sin [(x+y)/2] sin [(x-y)/2]
14
Q
tan 2A
A
(2 tan A)/(1-tan2A)
15
Q
cos(−θ)
A
cos θ