Show that none of the following is an identity:
sin2 θ + sin θ = 2
If the given equation is an identity, then it is true for every value of θ.
So, let θ = 30°
So, for θ = 30°, consider the L.H.S. = sin2 30° + sin 30°
= (1/2)2 + (1/2)
= (1/4) + (1/2)
= 3/4 ≠ 2
Therefore, L.H.S. ≠ R.H.S.
Thus, the given equation is not an identity.