Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If cot2 θ = 3 - a2, then cosec θ + cot3 θ. sec θ =?

Options:

(4 - a2)\(\frac{3}{2}\) 

(4 + a2)\(\frac{3}{2}\) 

(4 + a2)\(\frac{5}{2}\) 

(4 - a2)\(\frac{5}{2}\) 

Correct Answer:

(4 - a2)\(\frac{3}{2}\) 

Explanation:

Let put θ = 45°

⇒ cot2 θ = 3 - a2

⇒ 1 = 3 -  a2

⇒ a2 = 2

and

⇒ cosec θ + cot3θ . sec θ = cosec 45° + cot3 45° × sec 45°

= \(\sqrt {2}\) + \(\sqrt {2}\) = 2\(\sqrt {2}\)

Now put a2 = 2 in options and find answer

(4 - a2)\(\frac{3}{2}\) = (2)\(\frac{3}{2}\) = 2\(\sqrt {2}\) 

Hence, option (1) is correct answer.