Trig identities Flashcards
1
Q
tan (x) =
A
sin(x) / cos(x)
2
Q
cot(x)=
A
cos(x) / sin(x)
or
1/tan(x)
3
Q
sec(x)=
A
1/cos(x)
4
Q
csc(x)=
A
1/sin(x)
5
Q
What is the Pythagorean identity?
A
sin^2(x) + cos^2(x)= 1
6
Q
cos^2(x)=
A
1-sin^2(x)
7
Q
sin^2(x)=
A
1-cos^2(x)
8
Q
csc^2(x)=
A
1+cot^2(x)
9
Q
sec^2(x)=
A
1+tan^2(x)
10
Q
sin(2x)
A
2sin(x)cos(x)
11
Q
cos(2x)
A
cos^2(x) - sin^2(x)
or
2cos^2(x)-1
or
1-2sin^2(x)
12
Q
tan(2x)=
A
2tan(x) / (1-tan^2(x))
13
Q
sin (x/2)=
A
√(1-cos(x)) / 2
14
Q
cos (x/2) =
A
√(1+cos(x)) / 2
15
Q
tan (x/2) =
A
(1-cos(x)) / sin(x)
sin(x) / (1+cos(x))
√(1-cos(x) / 1+ cos(x)