Find theta: Solving csc & ctn Equations with x-6 & x+5

  • Thread starter Thread starter lucifer_x
  • Start date Start date
AI Thread Summary
To find theta given the equations csc(theta) = (x-6)/(x-2) and ctn(theta) = (x+5)/(x-2), one must first express sin(theta) and tan(theta) in terms of x using trigonometric identities. By applying the Pythagorean theorem, a triangle can be constructed to visualize the relationships between the sides and angles. The discussion emphasizes the importance of using trigonometric identities to transition between functions, such as converting secant to tangent. A simpler method involves drawing a triangle with appropriate side lengths based on the given ratios. The conversation highlights the distinction between functional inverses and multiplicative inverses in trigonometric contexts.
lucifer_x
Messages
15
Reaction score
0
if

csc theta=
x-6
x-2

and

ctn theta=
x+5
x-2

find theta
 
Physics news on Phys.org
You need to show us some work.

Here are some questions to get you moving.

What is sin \theta ?

What is Tan \theta ?

Now use what you know about the definition of sin and Tan to draw a triangle. Apply Pythagorean theorem.
 
First you need to solve for x. That means making use of a trigo identity to get theta out of the way. Express sin theta and cos theta in terms of x, then apply that trigo identity.
 
Trig identities are one way to shift from one function to another (for example, if you know sec(x)= a/b and want to find tan(x), write a trig identity that converts sec to tan, say tan2(x)= sec2(x)- 1 and so that tan2(x)= x2- 1 and tan(x)= \sqrt{a^2/b^2- 1}= .\sqrt{a^2- b^2}/b [/itex].

Still another, perhaps simpler, method is to draw a triangle with one angle x and write in appropriate lengths for the sides. In the above example, if sec(x)= a/b then, since sec= 1/cos or "hypotenuse over near side", our triangle would have hypotenuse a and near side b. By the Pythagorean theorem, the "opposite side" has length \sqrt{a^2- b^2} and so tan(x), "opposite side over near side", is \sqrt{a^2- b^2}/b

But don't use the word "reciprocals" here. Reciprocals are specifically the "multiplicative inverses". Here you are concerned with "functional inverses".
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
Back
Top