1.

If \(\frac{{sec\theta + tan\theta }}{{sec\theta - tan\theta }} = 5\) and θ is an acute angle, then the value of \(\frac{{3{{\cos }^2}\theta + 1}}{{3{{\cos }^2}\theta - 1}}\) is:  1. 42. 33. 14. 2

Answer» Correct Answer - Option 1 : 4

Given:

\(\frac{{secθ + tanθ }}{{secθ - tanθ }} = 5\)

Concept used:

secθ = Hypotenuse/Base, tanθ = perpendicular/base, cosθ = base/hypotenuse

Pythgorus theorem

Hypotenuse2 = Perpendicular2 + Base2

Calculation:

Let Perpendicular = P, Base = B, Hypotenuse = H

\(\frac{{secθ + tanθ }}{{secθ - tanθ }} = 5\)

⇒ {(H/B) + (P/B)}/{(H/B) - (P/B)} = 5/1

⇒ (H + P)/(H - P) = 5/1

⇒ H + P = 5      ----(1)

⇒ H - P = 1      ----(2)

Solve (1) and (2)

⇒ H = 3, P = 2

Hypotenuse2 = Perpendicular2 + Base2

⇒ Base = √5

\(\frac{{3{{\cos }^2}\theta + 1}}{{3{{\cos }^2}\theta - 1}}\)

⇒ {3 × (√5/3)2 + 1}/{3 × (√5/3)2 - 1}

⇒ (8/3)/(2/3)

⇒ 4

∴ The value is 4.



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