What is the value of Cos ( - \(\frac{17\pi}{3}\) )

Question

Question

This question was previously asked in

SSC CGL 2022 Tier-I Official Paper (Held On : 06 Dec 2022 Shift 2)

Answer 1

Given:

Cos ( - \(\frac{17\pi}{3}\) )

Concept used:

1. cos (- θ) = cos θ

2. cos is always positive in the fourth quadrant.

3. sin 30° = 1/2

Calculation:

Cos ( - \(\frac{17\pi}{3}\) )

⇒ Cos \(\frac{17\pi}{3}\)

⇒ Cos \(\frac{17\times 180^\circ}{3}\)

⇒ Cos \({17\times 60^\circ}\)

⇒ Cos 1020°

⇒ Cos \(({90^\circ \times 11 + 30^\circ})\)

⇒ Sin 30°

⇒ \(\frac{1}{2}\)

∴ The value of Cos ( - \(\frac{17\pi}{3}\) ) is \(\frac{1}{2}\).