Trig Identities

Question 1

sin^2(x) + cos^2(x)

Answer 1

= 1

Question 2

sin(x)/cos(x)

Answer 2

= tan(x)

Question 3

1/sin(x)

Answer 3

= cosec(x)

Question 4

1/cos(x)

Answer 4

= sec(x)

Question 5

1/tan(x)

Answer 5

= cot(x)

Question 6

sin(A±B)

Answer 6

= sinAcosB ± sinBcosA

Question 7

cos(A+B)

Answer 7

cosAcosB - sinAsinB

Question 8

cos(A-B)

Answer 8

cosAcosB + sinAsinB

Question 9

sin(2x)

Answer 9

= 2sin(x)cos(x)

Question 10

cos(2x) (three)

Answer 10

cos^2(x) - sin^2(x)
1-2sin^2(x)
2cos^2(x)-1

Question 11

sinAsinB

Answer 11

=(1/2)(cos(A-B) - cos(A+B))

Question 12

cosAcosB

Answer 12

=(1/2)(cos(A-B) + cos(A+B))

Question 13

sinAcosB

Answer 13

=(1/2)(sin(A-B) - sin(A+B))