X+6 less than or equal to 10
X+14 greater than or equal to 18
I think it would be the second question!
Answer: use desmos graphing calculator
Step-by-step explanation:
It's a value you should probably memorize:

You can derive it using some trigonometric identities, other known values of cosine, and properties of the cosine function. For example, using the double angle identity for cosine:

If
, then

and you probably know that
, so

When we take the square root, we should take the positive root because
whenever
:
