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
Answer:
The answer is-2.
Step-by-step explanation:
#Hope it helps uh......
Answer:
Step-by-step explanation:a/
slope m = [f(x)-f(3)]/(x-3)
b/
tangent y - f(3) = [lim m ,as x-->3](x-3)
1/2 of 20 is 20/2 which is 10.
All you really need to do here is to divide 20 by 2 to get 10.
Answer:
Step-by-step explanation:
To simplify this expression, first use the distributive property to distribute 
.
Simplify.
Combine like terms, 
and 
.
The simplification of 
is .
I hope this helps ^^
Good luck
