Trig Ids Flashcards
1
Q
cos^2(theta) + sin^2(theta)
A
=1
2
Q
1+tan^2(theta)
A
=sec^2(theta)
3
Q
cot^2(theta)+1
A
csc^2(theta)
4
Q
sin(-theta)
A
-sin(theta)
5
Q
cos(-theta)
A
cos(theta)
6
Q
Cos(theta+2pi)
A
Cos(theta)
7
Q
Sin(theta+2pi)
A
Sin(theta)
8
Q
Sin(x+y)
A
Sinxcosy + cosxsiny
9
Q
Cos(x+y)
A
Cosxcosy-sinxsiny
Switch the sign
10
Q
tan(x+y)
A
sin(x+y)/cos(x+y)=
Tanx + tany)/(1+tanxtany
11
Q
Sin(2x)
A
Sin(x+x)=
(sinxcosx+cosxsinx)
=2sinxcosx
12
Q
Cos(2x)
A
Cos(x+x)=
cosxcosx-sinxsinx
cos^2x-sin^2x
Cos^2x+sin^2x=1
Cos(x+x)=
(1-sin^2x)-(sin^2x)
=1-2sin^2x
Cos(2x)=
cos^2x-(1-cos^2x)
=2cos^2x-1
13
Q
Cos(2x)=2cos^2x-1
A
(1+cos(2x))/2
14
Q
Cos(2x)=1-2sin^2x
A
Sin^2x = (1-sin^2x)/2
15
Q
Sinxcosy
A
(1/2)(sin(x+y)+sin(x-y))
