I did my calculation and your answer should be 87.9
hope this helped :)
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
A trinomial is a polynomial with three terms. It can be determined if it is a difference of two squares when you factor it.
The resulting factor of a trinomial that is a difference of two squares is: a²<span> – b</span>²<span> = (a + b)(a – b) or (a – b)(a + b)</span>
You will notice that the middle term is missing. This means that the middle term zeroes out as a result of having the same number of different signs (+ and -)
The answer is false, it is only true for postulates, not conjectures.
