Question

The value of cos 255° + sin 195° is ______.

विकल्प

• `(sqrt(3) - 1)/(2sqrt(2))`

• `(sqrt(3) - 1)/sqrt(2)`

• `-[(sqrt(3) - 1)/sqrt(2)]`

• `(sqrt(3) + 1)/sqrt(2)`

Answer 1

The value of cos 255° + sin 195° is `underlinebb(-[(sqrt(3) - 1)/sqrt(2)]`.

Explanation:

Consider cos 255° + sin 195°

= cos(270° – 15°) + sin(180° + 15°)

= –sin15° – sin15°

= –2sin15°

= `-2[(sqrt(3) - 1)/(2sqrt(2))]`

= `-[(sqrt(3) - 1)/sqrt(2)]`