1. Regroup terms
x(x+5)=104
2. Expand
x^2+5x=104
3. Move all terms to one side
x^2+5x-104=0
4. Factor x^2+5x-104
(x-8)(x+13)=0
5. Solve for x
x=8 or x=-13
Since x<0 is not possible in this case, x=8
6. Finding the dimensions
We know that one side has to be x+5, and now that we know x:
8+5=13
13*8=104
The dimensions are 13 and 8, have a nice day :D
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
hope it will help u..........
The answer is definitely -4 1/8
