Find the exact value of cos (135) and sin (135).

To find the exact value of cos (135), you need the following formula: cos (a+b) = cos a • cos b - sin a • sin b So in this case, it would be: cos (135) = cos (45 + 90) = cos 45 • cos 90 - sin 45 • sin 90 = √ (2) / 2 · 0 - √ (2) / 2 · 1 = 0 - (√2) / 2 = - (√2) / 2.

To find the exact value of sin (135), you need the following formula: sin (a+b) = sin a • cos b - cos a + sin b So in this case, it would be sin (135) = sin (90 + 45) = sin 90 • cos 45 + cos 90 • sin 45 = (1 · (√2) / 2) + (0 · (√2) / 2) = (√2) / 2).

cos (135) = - (√2) / 2

sin (135) = (√2) / 2