Question

cos 135°
value how to find

Answer 1

Hello,
The value of cos 135° can be found by process of breaking it into two numbers of which the cos value is known.
Now,
135° = 90° +45°
So, cos135 = cos90 + sin 90-sin135( since cos 45 = sin 45)
(Also sin 45 = sin 90 - sin 135)

Now, we know cos 90 =0
And, sin 45 = -1 /root2
Sin 90 = 1
Sin135 = - 1/root3
So, cos135 = 0 - 1/root2
So, cos135 = - 1 /root 2

Hope this will be helping you.

WARM REGARDS
Sahil khirwal