Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If 7sin2 θ + 3cos2 θ = 4, 0 <  θ < 90°, then the value of \(\frac{tan^2 2 θ - sin^2  θ}{cot θ + cosec2 θ}\)?

Options:

\(\frac{7\sqrt {3 }}{20}\)

\(\frac{13\sqrt {3 }}{20}\)

\(\frac{11\sqrt {3 }}{20}\)

6\(\sqrt {3 }\)

Correct Answer:

\(\frac{11\sqrt {3 }}{20}\)

Explanation:

7sin² θ + 3cos² θ = 4

 θ = 30° satisfies the equation

⇒ \(\frac{tan^2 2 θ - sin^2 θ}{cot  θ + cosec2 θ}\) = \(\frac{tan^2 60° - sin^2 30°}{cot 30° + cosec 60°}\)

= \(\frac{3 -\frac{1}{4}}{\sqrt {3} + \frac{2}{\sqrt {3}}}\)

= \(\frac{\frac{11}{4}}{\frac{5}{\sqrt {3}}}\)

= \(\frac{11 \sqrt {3}}{20}\)