How Do You Solve tan(2x - 5) = cot(x + 5) in the Interval 0 < x < 90?

In summary, the conversation discusses finding the solution for the equation tan(2x - 5) = cot(x + 5) when 0 < x < 90. The first approach involves substituting cot(alpha) = tan(pi/2 - alpha) and applying arctan. The second approach involves using the identities for cosine and sine and solving for the angle when cosine of the sum of two angles is equal to 0. The conversation then discusses the value of the solution, which is found to be 30 degrees, and confirms that tangent and cotangent are recip
  • #1
Monoxdifly
MHB
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If 0 < x < 90, what is the solution of tan(2x - 5) = cot(x + 5)?
I got stuck in tan(2x - 5)tan(x + 5) = 1. What should I do after that?
 
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  • #2
Suppose we substitute $\cot\alpha=\tan(\frac\pi 2-\alpha)$ and apply $\arctan$? (Wondering)
 
  • #3
another approach ...

$\tan{\alpha} = \cot{\beta}$

$\dfrac{\sin{\alpha}}{\cos{\alpha}} = \dfrac{\cos{\beta}}{\sin{\beta}}$

$\cos{\alpha} \cdot \cos{\beta} = \sin{\alpha} \cdot \sin{\beta}$

$\cos{\alpha} \cdot \cos{\beta} - \sin{\alpha} \cdot \sin{\beta} = 0$

$\cos(\alpha + \beta) = 0$
 
  • #4
skeeter said:
another approach ...

$\tan{\alpha} = \cot{\beta}$

$\dfrac{\sin{\alpha}}{\cos{\alpha}} = \dfrac{\cos{\beta}}{\sin{\beta}}$

$\cos{\alpha} \cdot \cos{\beta} = \sin{\alpha} \cdot \sin{\beta}$

$\cos{\alpha} \cdot \cos{\beta} - \sin{\alpha} \cdot \sin{\beta} = 0$

$\cos(\alpha + \beta) = 0$

I like this other approach since I can comprehend it easier. I got \(\displaystyle 30^{\circ}\) this way. Is that right?
 
  • #5
Monoxdifly said:
I like this other approach since I can comprehend it easier. I got \(\displaystyle 30^{\circ}\) this way. Is that right?

substitute your solution into the original equation ...

is $\tan(55^\circ) = \cot(35^\circ)$ ?
 
  • #6
skeeter said:
substitute your solution into the original equation ...

is $\tan(55^\circ) = \cot(35^\circ)$ ?

I don't know, I can't count that without using a calculator or manually measuring the ratios with ruler and protactor.
Oh wait, I can just draw a random right triangle and label the angles.
Oh yes, $\tan(55^\circ) = \cot(35^\circ)$.
 
  • #7

FAQ: How Do You Solve tan(2x - 5) = cot(x + 5) in the Interval 0 < x < 90?

What is a trigonometric equation?

A trigonometric equation is an equation that involves trigonometric functions such as sine, cosine, and tangent. These equations are used to solve problems related to angles and triangles.

How do I solve a trigonometric equation?

To solve a trigonometric equation, you need to use algebraic techniques to isolate the trigonometric function and then use trigonometric identities to simplify the equation. You can also use a calculator to find the solutions.

What are the common trigonometric identities used in solving equations?

The most common trigonometric identities used in solving equations are the Pythagorean identities, sum and difference identities, and double angle identities.

How do I know if my solution to a trigonometric equation is correct?

You can check your solution by substituting it back into the original equation and simplifying. If the resulting equation is true, then your solution is correct.

What are the real-life applications of trigonometric equations?

Trigonometric equations are used in many fields such as physics, engineering, and astronomy to solve real-world problems involving angles and distances. They are also used in navigation, surveying, and construction to determine the measurements of triangles and other geometric shapes.

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