Solving sin(x)/sin(x+215) = ab/cd

  • Thread starter tony873004
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In summary, the conversation discusses an equation involving sin and a question about simplifying it. The equation is solved using the property sin(x) = bsin(x+a) = bsin(x)cos(a) + bcos(x)sin(a) and the inverse tangent function. Thanks are given to LCKurtz for the help.
  • #1
tony873004
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This isn't homework, but I can't seem to access the math forum at the moment, so I thought I'd ask here.

Homework Statement


sin(x)/sin(x+215) = ab/cd.
Solve for x

Homework Equations


Is there any property for sin x / sin y so I can simplify this?
 
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  • #2
Your equation has the form sin(x) = bsin(x+a) = bsin(x)cos(a) + bcos(x)sin(a)
= bsin(x)(cos(a) + bsin(a))

sin(x)(1-bcos(a)) = bcos(x)sin(a)
[tex]\frac{\sin(x)}{\cos(x)}=\tan(x)=\frac{b\sin(a)}{1-b\cos(a)}[/tex]

You can now solve using the inverse tangent function.
 
  • #3
Thanks LCKurtz!
 

1. How do I solve the equation sin(x)/sin(x+215) = ab/cd?

To solve this equation, you can use the trigonometric identity sin(a)/sin(b) = cot(b-a). In this case, a = x and b = x+215. So, the equation becomes cot(x+215-x) = cot(215) = ab/cd. From here, you can take the inverse cotangent (arccot) of both sides to find the value of x.

2. Can this equation be solved without using trigonometric identities?

Yes, this equation can also be solved using algebraic manipulation. You can multiply both sides of the equation by sin(x+215) to get rid of the fractions. Then, use the Pythagorean identity sin^2(x) + cos^2(x) = 1 to simplify the equation and solve for x.

3. Are there any restrictions on the values of x that can make this equation true?

Yes, there are restrictions on the values of x. Since the equation involves division by sin(x+215), x+215 cannot equal 0, pi, 2pi, etc. So, the possible values of x are all real numbers except for any integer multiple of pi - 215.

4. Can this equation have multiple solutions?

Yes, this equation can have multiple solutions. Since trigonometric functions are periodic, there can be an infinite number of values for x that satisfy the equation. However, if the equation is restricted to a specific interval, there may be only one solution.

5. How can I check if my solution to this equation is correct?

To check if your solution is correct, you can plug the value of x into the original equation and see if it satisfies the equation. You can also use a graphing calculator to graph both sides of the equation and see if they intersect at the value of x you found.

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