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:
Thus, every integer is a rational number. Clearly, 3/2,-5/3, etc. are rational numbers but they are not integers. Hence, every integer is a rational number but a rational number need not be an integer.
Step-by-step explanation:
Answer:
well it simply tells you if you think your right on all of them then press yes if not press no
Answer:
D and E
Step-by-step explanation:
Perimeter = 4s
4(x + 8)
4x + 32
Multiply the price of popcorn by the number of bags so 6b.
Multiply the price of candy by the number bought, so 3.25c
Add those together to get total :
6b + 3.25c
Now the most she can spend is 50 so set the equation to less than it equal to what she can spend:
6b + 3.25c <= 50
