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:
a=-3/7 b=-2/8 c=-0.2
Step-by-step explanation:
Answer:
9.06 units
Step-by-step explanation:
The distance formula for points on a graph is basically the Pythagorean Theorem
√(x2 - x1)² + (y2 - y1)²
Plug in the values and you'll get √82, which equals about 9.05539, or 9.06
Be more specific, what your talking about ?
Answer:
-3(8+2)=-30
Step-by-step explanation:
-3(8+2)
(8+2)=10
-3×10=-30
