Question

What is the exact value of cos 105°?

Answer 1

@kayders1997

Answer 2

A calculator will not give the exact value.

Answer 3

Use the cosine of a sum formla:

cos(A+B) = cos A cos B − sin A sin B

Answer 4

Let A = 60 and B = 45. Angles A and B sum to 105.

Answer 5

I got 1/4 and something BFF else

Answer 6

Please post work.

Answer 7

Make A 60 degrees, and B 45 degrees
(0.5)(√2/2)-(√3/2)(√2/2)

I got (√2 - √6)4

Answer 8

That's exactly what I got

Answer 9

Sorry, forgot division sign
(√2 - √6)/4