Q. 75.0( 1 Vote )

# If 0 < θ < 90, θ, sinθ = cos30, then obtain the value of 2tan^{2}θ — 1.

Answer :

cos(90–θ ) = sinθ

tan(90–θ ) = cotθ

sin(90–θ ) = cosθ

cot(90–θ ) = tanθ

cosec(90–θ ) = secθ

sec(90–θ) = cosecθ

sinθ = cos30

⇒ θ = 60

Now, 2tan^{2}θ – 1

= 2tan^{2}60 – 1

= 2(√3)^{2} – 1

= 5

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