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

Question 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 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
sin t + cos^{2} t / sin t =
a) sin t
b) csc t
c) sec t
d) cos t

Question 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 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
sin (x) + sin(x  π) + sin(x + π) =
a) sin(x)
b) sin (x)
c) sec (x)
d) cos (x)