Question

Which of the following number (s) is/are rational?
A) sin 15° B) cos 15° C) sin15° cos15° D) sin 15° cos 75°

Answer 1

sin 15 , cos 15, sin15 cos 75 all involves √3

so irrational

sin 15 cos 15 = 1/2 2 sin 15 cos15

As 2 sin 15 cos 15 = sin 30

So sin 30/2 = 1/4 = 0.25 which is rational


So sin15 cos 15 is answer

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