For 0 < θ < π/4, let a = ((sinθ)sinθ)(log2cosθ), b = ((cosθ)sinθ)(log2sinθ), c = ((sinθ)cosθ)(log2cosθ) and d = ((sinθ)sinθ)(log2sinθ). Then, the median value in the sequence a, b, c, d is
Explanation:
0 < θ < π/4, let's take θ = 30°
sin30° = 1/2 = 0.5, cos30° = √3/2 = 0.866
a = ((sinθ)sinθ)(log2cosθ), ⇒ a = ((1/2)1/2)(log20.866)
b = ((cosθ)sinθ)(log2sinθ), ⇒ b = ((0.866)1/2)(log21/2),
c = ((sinθ)cosθ)(log2cosθ) ⇒ c = ((1/2)0.866)(log20.866)
d = ((sinθ)sinθ)(log2sinθ) ⇒ d = ((1/2)1/2)(log21/2)
(1/2)0.5 > (1/2)0.866 and (log20.866) is negative ∴ c is greater than a.
Similarly, c > a > d > b.
∴ Median of these four numbers = average of 2 middle numbers = (a + d)/2
Hence, option (b).
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