Q36 of 186 Page 332

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.


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