Solve for x:

cos (x) = 3x/(2pi)

The asnwer is pi /3 but how is it solved algebraically???

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- May 10th 2011, 08:50 PMbakchormeeSolving a Trigonometric Equation
Solve for x:

cos (x) = 3x/(2pi)

The asnwer is pi /3 but how is it solved algebraically??? - May 10th 2011, 08:56 PMProve It
I don't think this can be solved algebraically...

- May 10th 2011, 08:58 PMbakchormee
ok. Then how can I prove that pi/3 is the answer?

- May 10th 2011, 09:04 PMProve It
LHS = cos(pi/3) = 1/2

RHS = 3(pi/3)/(2pi) = pi/(2pi) = 1/2 = LHS.

So x = pi/3 is a solution. - May 10th 2011, 09:17 PMbakchormee
- May 10th 2011, 09:28 PMProve It
- May 10th 2011, 09:30 PMbakchormee
What do you mean by numerical methods?

Yes by graphing it, the point of intersection if x = pi/3.

But i need to know it is derived...? - May 10th 2011, 09:32 PMProve It
Numerical methods are iterative methods, such as the Bisection Method or Newton's Method. Google them.

Like I said, this point of intersection can NOT be solved algebraically, because you have a trigonometric function on one side and a polynomial function on the other. There is no way to combine them... - May 10th 2011, 09:51 PMbakchormee
Thanks for that.

I having problems deriving x to show the prove though.....