Question

Find the value of cos 135°.

(a) \(\frac {1}{\sqrt {2}}\)

(b) √2

(c) -√2

(d) \(\frac {-1}{\sqrt {2}}\)

This question was addressed to me during a job interview.

The query is from Trigonometric Ratios of Complementary Angles in division Trigonometry of Mathematics – Class 10

Answer 1

Correct option is (d) \(\frac {-1}{\sqrt {2}}\)

Explanation: Cos 135° = Cos (90° + 45°)

= -Sin 45°

= \(\frac {-1}{\sqrt {2}}\)