Question

solve 2cos^2x-5cosx+2=0 for the principal values of x.
a)60
b)60 and 300
c) 30
d) 0 and 30

Answer 1

where is your previous problem ? I was solving it :)

Answer 2

i got the answer thanks!!

Answer 3

one of the rules you need is : cos^2(x) = 1/2 + 1/2 cos(2x)

Answer 4

then plug in 60 degrees. and its cosine value is 1/2.

Answer 5

ok and then how can i use that to get the answer?

Answer 6

@gursu