SSC CHSL 2021 PYQ — Question 75

The correct answer is option 3 i.e. 322.

sin θ + cosec θ = 7

⇒ sin θ + $\frac{1}{sin θ}$ = 7

Now,

sin³ θ + $\frac{1}{sin^3 θ}$ = (7)³ - 3(7)    [x³ + $\frac{1}{x^3}$ = (x + $\frac{1}{x}$)³ - 3(x + $\frac{1}{x}$)]

⇒ 343 - 21 = 322