Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If the sinθ + cosθ =\(\sqrt{5}\) sin(90°-θ), then find the value of cotθ.

Options:

\(\frac{\sqrt {5}-1}{4}\)

\(\frac{\sqrt {5}+1}{4}\)

\(\frac{\sqrt {5}+1}{3}\)

\(\frac{\sqrt {3}+\sqrt {5}}{2}\)

Correct Answer:

\(\frac{\sqrt {5}+1}{4}\)

Explanation:

sinθ + cosθ =\(\sqrt{5}\)cosθ    (sin(90°-θ) = cosθ)

sinθ =\(\sqrt{5}\)cosθ - cosθ

sinθ =cosθ(\(\sqrt{5}-1\))

\(\frac{cosθ}{sinθ}\) = \(\frac{1}{\sqrt {5}-1}\)

cotθ = \(\frac{\sqrt {5}+1}{4}\)  (By rationalisation)