# Questions on Trigonometric Identities

Multiple choice questions on trigonometric identities with answers at the bottom of the page.

### Question 1

Which of the following is not an identity?
a) sin
2 a+cos 2 a = 1
b) sin a = tan a * cos a
c) 1 + cot
2 a = csc 2 a
d) 1 - sec
2 a = tan 2 a

### Question 2

Which of the following is an identity?
a) sin (a) cos (a) = (1/2) sin(2 a)
b) sin a + cos a = 1
c) sin(-a) = sin a
d) tan a = cos a / sin a

### Question 3

sin t + cos2 t / sin t =

a) sin t
b) csc t
c) sec t
d) cos t

### Question 4

Which of the following is not an identity?
a) tan(2 t) = 2 tan (t)
b) sin
2 a = 1 - cos 2 a
c) sin(-t) = - sin(t)
d) sec(-t) = sec(t)

### Question 5

Which of the following is an identity?
a) sin
2 u = 1 + cos 2 u
b) cot u = sin u * cos u
c) sin
2 u = 1 - 1 / sec 2 u
d) cos(-u) = - cos u

### Question 6

sin (x) + sin(x - π) + sin(x + π) =

a) -sin(x)
b) sin (x)
c) sec (x)
d) cos (x)