Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If sinα + cosecα = tan (\(\frac{\pi}{3}\))

Find the value of (sin3α + cosec3α)

Options:

\(\frac{1}{2}\)

0

1

\(\frac{3}{2}\)

Correct Answer:

0

Explanation:

Formula I → [sinα = \(\frac{1}{cosecα}\)]

Formula II → [If x + \(\frac{1}{x}\) = y and x3 + \(\frac{1}{x^3}\) = y3 - 3y]

So,

⇒sinα + \(\frac{1}{sinα}\) = tan \(\frac{180°}{3}\) = tan60°

⇒ sinα + \(\frac{1}{sinα}\) = \(\sqrt {3}\)

Cubing both sides,

⇒ sin3α + \(\frac{1}{sin^3α}\) = (\(\sqrt {3}\))3 - 3\(\sqrt {3}\)

⇒ sin3α + cosec3α = 0