Question

Given that cos (x) = k
what does cos (2x) = ?

Thanks in advance :)

Answer 1

Answer:

(2x) = 2k

Step-by-step explanation:

If x = k, then 1x=1k, then 2x=2k

Answer 2

Answer:

2k² - 1

Step-by-step explanation:

cos x =k

cos 2x = 2 cos ² x - 1

           = 2k² - 1