Discover the Solution for tan(x)=sin(2x) in Just a Few Simple Steps!

  • Thread starter princiebebe57
  • Start date
In summary, to find the solution points of tan(x)=sin(2x), one can express both sides in terms of sin(x) and cos(x) and then use the fact that (a-b)^2 = (a+b)(a-b) to solve for x. Alternatively, one could plot the functions and look for intersection points, but using the suggested method may yield more accurate answers.
  • #1
princiebebe57
31
0
How do you find the solution tan(x)=sin(2x)? :confused:
 
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  • #2
Can you express both sides in terms of sin(x) and cos(x)? That might be a good place to start.
 
  • #3
No...do i have to do that to find all the solution points?
 
  • #4
princiebebe57 said:
No...do i have to do that to find all the solution points?

You could plot them and look for the intersection points.
But cristo's suggestion would probably yield more accurate ["closed form"] answers. (Be careful not to inadvertently throw away solutions.)
 
Last edited:
  • #5
You can easily do it using the fact that:

[tex]
\begin{array}{l}
\tan x \equiv \frac{{\sin x}}{{\cos x}} \\
\sin (2x) \equiv 2\sin x\cos x \\
\end{array}
[/tex]
 
  • #6
square both sides...then make use of (a-b)^2 = (a+b)(a-b)
 
  • #7
unscientific said:
square both sides...then make use of (a-b)^2 = (a+b)(a-b)

um...
(a-b)^2 = a^2 - 2ab + b^2
a^2 - b^2 = (a+b)(a-b)
 

What is the equation that needs to be solved?

The equation that needs to be solved is tan(x) = sin(2x).

Why is it important to find the solution for this equation?

Finding the solution for this equation is important because it allows us to understand the relationship between the tangent and sine functions, and it can also be applied to various real-world problems in fields such as physics, engineering, and astronomy.

What are the steps to solve this equation?

The steps to solve this equation are:
1. Use the double angle formula for sine to rewrite the equation as tan(x) = 2sin(x)cos(x).
2. Divide both sides by cos(x) to get tan(x)/cos(x) = 2sin(x).
3. Use the identity tan(x)/cos(x) = sin(x)/cos^2(x) to rewrite the equation as sin(x)/cos^2(x) = 2sin(x).
4. Simplify to get sin(x) = 2sin(x)cos^2(x).
5. Use the identity sin^2(x) + cos^2(x) = 1 to rewrite the equation as sin(x) = 2sin(x)(1-sin^2(x)).
6. Distribute and rearrange terms to get 2sin^3(x) - sin(x) + 1 = 0.
7. Use the substitution u = sin(x) to rewrite the equation as 2u^3 - u + 1 = 0.
8. Use the rational root theorem or synthetic division to find the solutions for u.
9. Substitute the solutions back into the equation u = sin(x) to get the solutions for x.

What is the significance of the solutions for this equation?

The solutions for this equation represent the values of x that satisfy the equation and make both sides equal to each other. These solutions also represent the intersection points of the graphs of the tangent and sine functions.

Are there any special considerations when solving this equation?

Yes, when solving this equation, it is important to check for extraneous solutions. This means that sometimes, the solutions obtained may not be valid for the original equation, so they need to be checked and eliminated if necessary. It is also important to follow the order of operations and use the correct identities to simplify the equation correctly.

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