Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If $ sin α + cosec α =  tan\frac{\pi}{3}$, then the value of $(sin^3 α +cosec^3α)$ is equal to :

Options:

$\frac{1}{2}$

1

0

$\frac{3}{2}$

Correct Answer:

0

Explanation:

sin α + cosec α = tan \(\frac{π}{3}\)

{ \(\frac{π}{3}\) = \(\frac{180º}{3}\) = 60º   & tan60º = \(\sqrt {3 }\) }

sin α + cosec α = tan60º

sin α + cosec α = \(\sqrt {3 }\) 

sin α  + \(\frac{1}{sin α}\) = \(\sqrt {3 }\)  

We know,

If x + \(\frac{1}{x}\) = a

then  x³ + \(\frac{1}{x³}\) = a³ - 3a

Now,

sin³ α  + \(\frac{1}{sin³ α}\) = (\(\sqrt {3 }\))³ - 3(\(\sqrt {3 }\))

= 3(\(\sqrt {3 }\)) - 3(\(\sqrt {3 }\))

= 0