Question

cos^2x + 2 cos x + 1 = 0

Answer 1

Find all solutions

Answer 2

\(\LARGE\color{blue}{ \bf cos^2(x) + 2 cos( x) + 1 = 0 }\) factor just like doing a^2+2a+1=(a=1)^2


\(\LARGE\color{blue}{ \bf ( cos~x+ 1) ^2= 0 }\) take square root of both sides



\(\LARGE\color{blue}{ \bf cos~x+ 1= 0 }\)


\(\LARGE\color{blue}{ \bf cos~x=-1 }\)