Trig identities

Question 1

tan x (QI)

Answer 1

sin x/cos x

Question 2

cot x (QI)

Answer 2

cos x/ sin x

Question 3

sin x (RI)

Answer 3

1/ csc x

Question 4

cos x (RI)

Answer 4

1/ sec x

Question 5

tan x (RI)

Answer 5

1/ cot x

Question 6

cot x (RI)

Answer 6

1/ tan x

Question 7

sec x (RI)

Answer 7

1/ cos x

Question 8

csc x (RI)

Answer 8

1/ sin x

Question 9

sin^2 x + ______ = 1

Answer 9

cos^2 x

Question 10

sec^2 x + ______= 1

Answer 10

tan^2 x

Question 11

csc^2 x - ______= 1

Answer 11

cot^2 x

Question 12

sin (A ± B)

Answer 12

sin A cos B ± cos A Sin B

Question 13

cos (A ± B)

Answer 13

cos A cos B ± sin A sin B

Question 14

tan (A ± B)

Answer 14

Tan A ± tan B/ 1 tan(A) tan(B)

Question 15

sin (2θ)

Answer 15

2 sinθ cosθ

Question 16

cos (2θ)

Answer 16

cos^2 θ- sin^2 θ
2cos^2 θ -1
1- 2co^2 θ

Question 17

tan (2θ)

Answer 17

2tanθ/1- tan^2θ

Question 18

half angle
sin^2θ

Answer 18

1-cos(2θ)/2

Question 19

half angle
cos^2θ

Answer 19

1+cos(2θ)/2

Question 20

half angle
tan^2θ

Answer 20

1-cos(2θ)/1+cos(2θ)

Question 21

Sin A sin B

Answer 21

[cos (a-b) - cos (a+b)]/2

Question 22

Cos A cos B

Answer 22

[cos (a-b) + cos(a+b)]/2

Question 23

sin A cos B

Answer 23

[sin(a-b) + sin(a+b)]/2

Question 24

Cos A sin B

Answer 24

[sin (a-b) - sin(a+b)]/2