Question

Find the value of following trigonometric ratios:

(i) sin 135°, cos 135°, tan 135°, cot 135°, sec 135°, cosec 135°

(ii) sin 150°, cos 150°, tan 150°, cot 150°, sec 150°, cosec 150°

Answer 1

(i) sin 135° = sin(90° + 45°)

= cos 45° = \(\frac{1}{\sqrt2}\) [∵ sin (90° + θ) = cos θ]

cos 135° = cos (90° + 45°)

= - sin 45° = \(-\frac{1}{\sqrt2}\)

tan 135° = tan (90° + 45°)

= - cos 45° = - 1 [∵tan (90° + θ) = - cot θ]

cot 135° = cot (90° + 45°)

= - tan 45° = - 1 [∵cot (90° + θ) = - tan θ]

(ii) sin 150° = sin(90° + 60°) = cos 60° [∵ sin (90° + θ) = cos θ] \(\frac{1}{2}\)