If 0 < θ < 90 and sin θ=cos 30, then 2 tan ^{2} θ-1=ldots ldots ldots ldots .

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8. Introduction to Trigonometry

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If $0 < \theta < 90$ and $\sin \theta=\cos 30,$ then $2 \tan ^{2} \theta-1=\ldots \ldots \ldots \ldots .$

A

$5$

B

$4$

C

$3$

D

$0$

Solution

$\sin \theta=\cos 30 \quad \therefore \sin \theta=\frac{\sqrt{3}}{2} \quad \therefore \theta=60$

Now, $2 \tan ^{2} \theta-1=2 \tan ^{2} 60-1=2(\sqrt{3})^{2}-1=6-1=5$

Standard 10

Mathematics

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