<p>solve for x
arccos (x²-4x+5/2)=2pi/3
cos of pi/3 is equal to 1/2 so 2pi is equal to 2 times 1/2 which =1 i subtracted then 1 over to make it x²-4x+3/2=0 that was all i did up to was i suppose to use complete the square method or was i suppose to do it that way</p>
<p>cos(2pi/3)=x^2-4x+5/2</p>
<p>You got it from there I bet.</p>
<p>Is this precalc hw?</p>
<p>a take home test but i kinda miss out on some of the material so i`m not sure how to do it</p>
<p>oh, i see.</p>
<p>yeah so any suggestions?</p>
<p>cos(2pi/3)=x^2-4x+5/2
-1/2=x^2-4x+5/2
x^2 -4x+3=0
(x-3)(x-1)=0
x-3=0 x-1=0
x=3,1</p>
<p>how come it is 1 tho i mean what i did was right.right ? i mean pi/3 is equal to 60degrees and the cos of 60 degrees is 1/2 so 2pi/3 would mean 2 times pi/3 which is 1</p>
<p>oh i see now 2pi/3 is 120 degree which puts it in the second quadrant since its cos and cos is negetive in the second quadrant then it would mean -1/2right ?</p>