Question

The value of this trigonometric equation is

Answer 1

Answer:

Explanation:

this is the solution for your question.

Answer 2

Solution:

We need to find:

cos(105°)

It can be written as

cos(60° + 45°)

Now,

simplifying using

cos(A + B) = cosAcosB - sinAsinB

Similarly

→ cos(60° + 45°) = cos60°cos45° - sin60°sin45°

Now

• cos60° = 1/2
• cos45° = 1/√2
• sin60° = √3/2
• sin45° = 1/√2

substituting the values we have

→ cos(105°) = (1/2)(1/√2) - (√3/2)(1/√2)

→ cos105° = 1/2√2 - √3/2√2

→ cos105° = (1 - √3)/2√2

Hence, cos105° = (1 - √3)/2√2