00:01
Hi, it is given that x1 x2 belongs to 0 to pi, not including 0 and pi not the values of x that is fine the equation was the equation is given here you need to find out one over pi x1 plus x2 and so on so from this equation you need to find out x1 and x2 and then evaluate this expression let's first find out this series here so let's work on this is given as 1 plus modulus cos x plus plus co square x plus modulus cos x cube and so on we have till infinity so it can be given us one plus modulus cos x plus now co square x is always positive even if put modulus cos x here and do it square then nothing will change because result here is positive here also we here, cosx is coming out to be modulus process is positive and it's square it's coming out to be positive.
01:07
So we can write like this plus we have sound till infinity.
01:13
Now it is a gp here, infinite gp and some of the series is given as a over 1 negative r.
01:21
The first term here we have 1.
01:24
R is modulus cosx.
01:28
Let's look at here if r is less than 1.
01:30
Here we have x belong to 0 to pi.
01:34
So 0 to pi we have cos x.
01:37
It's always less than 1.
01:39
So we get r less than 1.
01:44
So we can apply s infinity.
01:47
That is given as 1 over 1 negative modulus cos x.
01:54
Let's put back that in this equation.
02:00
So we get 27 is 3 cube.
02:03
So we get 3 to the power 3 over 1 negative modulus cosx equals 9 cube is given as 3 square cube that will be 3 to the power 6 compare this so the exponents are equal so we get 3 over 1 negative modulus 4 6 equals 6 so from here we get more cos x equal 1 over 2.
02:40
Now more corset, more cosex is 1 over 2.
02:44
That means cosex can take positive value or negative value.
02:48
So we have cosex is given as 1 by 2 and also negative 1 over 2.
02:59
Now if you just look at the graph 4 .0 2 pi by 2 for cosex the graph is like this...