Question

using triple angle formula.Find the value of cos 135°

Answer 1

Answer:

-1/root 2

Step-by-step explanation:

cos 135 = cos (90+45)

= cos 90. cos 45 - sin 90. sin 45

= -1 * (1/root 2)

Answer 2

Answer:

cos 135= cos180-45= -cos 45= -1/root 2