SSC CGL 2022 PYQ — Question 66

The correct answer is Option 2 i.e. $1\over6$.

Concept Used:

$\sin 3\theta = 3\sin\theta - 4 \sin^3\theta$

Explanation:

Accoding to the given question,

$sin 10° – {4\over 3} sin^3 10°$ = ${3sin 10° – 4 sin^3 10°}\over 3$

⇒ $\sin 3(10°) \over 3$

⇒ ${1 \over 3} \times \sin30°$ = ${1 \over 3}\times{1 \over 2}$ = $1\over6$

Hence the value of $sin 10° – {4\over 3} sin^3 10°$ is $1\over6$ .