cos (2x) = cos x
2 cos^2 x -1 = cos x using the double angle formula
2 cos ^2 x -cos x -1 =0
factor
(2 cos x+1) ( cos x -1) = 0
using the zero product property
2 cos x+1 =0 cos x -1 =0
2 cos x = -1 cos x =1
cos x = -1/2 cos x=1
taking the arccos of each side
arccos cos x = arccos (-1/2) arccos cos x = arccos 1
x = 120 degrees x=-120 degrees x=0
remember you get 2 values ( 2nd and 3rd quadrant)
these are the principal values
now we need to add 360
x = 120+ 360n x=-120+ 360n x = 0 + 360n where n is an integer
For this case we have that by definition, the Pythagorean theorem states that:

Where:
a, b: Are the legs
c: It is the hypotenuse
According to the figure we have to:

Substituting in the formula we have:

Answer:
Option D
1.0 2.39 3.3 4.-17 5.. 15 6. -24 7. 43 8. 39 9. -11 10.-17
Answer:
Option b is correct
.
Step-by-step explanation:
Domain is the set of all possible values of x where function is defined.
Given the function:

To find the domain of the given function:
Exclude the values of x, for which function is not defined
Set denominator = 0

By zero product property;
and 
⇒x = 0 and 
⇒x = 0 and 
Therefore, the domain of the given function is:

What's the question darlenneLopez