We have to find the value of the expression 
We know that the below values.
Hence, in order to find the value of the given expression, we can first rewrite it in terms of 
Now, we know that 
Hence, we have
C is the correct option.
This is the concept of algebra, to solve the expression we proceed as follows;
cos 2x-cosx=0
cos 2x=cosx
but:
cos 2x+1=2(cos^2x)
thereore;
from:
cos 2x=cos x
adding 1 on both sides we get:
cos 2x+1=cos x+1
2(cos^2x)=cosx+1
suppose;
cos x=a
thus;
2a^2=a+1
a^2-1/2a-1/2=0
solving the above quadratic we get:
a=-0.5 and a=1
when a=-0.5
cosx=-0.5
x=120=2/3π
when x=1
cos x=1
x=0
the answer is:
x=0 or x=2/3π
Answer:
so 9:20
Step-by-step explanation:
I'm confused by this question
Answer:
3
Step-by-step explanation:
