Answer:
x = pi/2 + 2 pi n x = pi + 2 pi n where n is an integer
x = 5pi /3 + 2 pi n
Step-by-step explanation:
8 cos^2 x + 4 cos x-4 = 0
Divide by 4
2 cos^2 x + cos x-1 = 0
Let u = cos x
2 u^2 +u -1 =0
Factor
(2u -1) ( u+1) = 0
Using the zero product property
2u-1 =0 u+1 =0
u = 1/2 u = -1
Substitute cosx for u
cos x = 1/2 cos x = -1
Take the inverse cos on each side
cos ^-1(cos x) = cos ^-1(1/2) cos ^-1( cos x) =cos ^-1( -1)
x = pi/2 + 2 pi n x = pi + 2 pi n where n is an integer
x = 5pi /3 + 2 pi n
Answer:
I think is c
Step-by-step explanation:
Check the picture below.
let's bear in mind that the segment MN is simply the sum of MQ + QN, and since M and N are midpoints, they cut that respective section into two equal halves.
![\bf \cfrac{~~\begin{matrix} 10QR \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~}{~~\begin{matrix} 6QR \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~}\implies \cfrac{5}{3}](https://tex.z-dn.net/?f=%5Cbf%20%5Ccfrac%7B~~%5Cbegin%7Bmatrix%7D%2010QR%20%5C%5C%5B-0.7em%5D%5Ccline%7B1-1%7D%5C%5C%5B-5pt%5D%5Cend%7Bmatrix%7D~~%7D%7B~~%5Cbegin%7Bmatrix%7D%206QR%20%5C%5C%5B-0.7em%5D%5Ccline%7B1-1%7D%5C%5C%5B-5pt%5D%5Cend%7Bmatrix%7D~~%7D%5Cimplies%20%5Ccfrac%7B5%7D%7B3%7D)
