Math Problem Statement

how to go from tan-1theta = 2-root3 to pi/12

Solution

To solve the equation tan1(θ)=23\tan^{-1}(\theta) = 2 - \sqrt{3} and deduce that θ=tan(π/12)\theta = \tan(\pi/12), follow these steps:


1. Understanding the equation

The given equation is: tan1(θ)=23\tan^{-1}(\theta) = 2 - \sqrt{3} This means that the angle whose tangent is θ\theta equals 232 - \sqrt{3}. Therefore: θ=tan(23)\theta = \tan(2 - \sqrt{3})


2. Relating to a known angle

From trigonometry, you aim to relate 232 - \sqrt{3} to a known angle in radians. Observe that the given value 232 - \sqrt{3} is not a direct angle but corresponds to a well-known trigonometric relationship at π/12\pi/12 radians.


3. Recognizing the tangent value

From trigonometric tables or properties, we know: tan(π12)=23\tan\left(\frac{\pi}{12}\right) = 2 - \sqrt{3}

This is a standard result in trigonometry derived from angle-sum identities: tan(π12)=tan(π4π3)\tan\left(\frac{\pi}{12}\right) = \tan\left(\frac{\pi}{4} - \frac{\pi}{3}\right)

Using the tangent subtraction identity: tan(ab)=tan(a)tan(b)1+tan(a)tan(b)\tan(a - b) = \frac{\tan(a) - \tan(b)}{1 + \tan(a)\tan(b)} Let a=π4a = \frac{\pi}{4} and b=π3b = \frac{\pi}{3}. Then: tan(π12)=tan(π4)tan(π3)1+tan(π4)tan(π3)\tan\left(\frac{\pi}{12}\right) = \frac{\tan\left(\frac{\pi}{4}\right) - \tan\left(\frac{\pi}{3}\right)}{1 + \tan\left(\frac{\pi}{4}\right)\tan\left(\frac{\pi}{3}\right)}

Substituting tan(π4)=1\tan\left(\frac{\pi}{4}\right) = 1 and tan(π3)=3\tan\left(\frac{\pi}{3}\right) = \sqrt{3}: tan(π12)=131+13=131+3\tan\left(\frac{\pi}{12}\right) = \frac{1 - \sqrt{3}}{1 + 1\cdot\sqrt{3}} = \frac{1 - \sqrt{3}}{1 + \sqrt{3}}

Now simplify: tan(π12)=(13)(13)(1+3)(13)=123+313=4232=23\tan\left(\frac{\pi}{12}\right) = \frac{(1 - \sqrt{3})(1 - \sqrt{3})}{(1 + \sqrt{3})(1 - \sqrt{3})} = \frac{1 - 2\sqrt{3} + 3}{1 - 3} = \frac{4 - 2\sqrt{3}}{-2} = 2 - \sqrt{3}

Thus: tan(π12)=23\tan\left(\frac{\pi}{12}\right) = 2 - \sqrt{3}


4. Conclusion

The equation tan1(θ)=23\tan^{-1}(\theta) = 2 - \sqrt{3} implies: θ=tan(π/12)\theta = \tan(\pi/12)


Would you like me to clarify any steps further or explore a different approach?

5 Related Questions:

  1. How is tan(π/12)\tan(\pi/12) derived from angle subtraction formulas?
  2. What are the key steps to simplify tangent expressions involving square roots?
  3. How does the identity tan(ab)\tan(a - b) work for π/4π/3\pi/4 - \pi/3?
  4. Can you show how to verify tan1(23)=π/12\tan^{-1}(2 - \sqrt{3}) = \pi/12?
  5. Why is π/12\pi/12 significant in trigonometry?

Tip: Memorizing common trigonometric values and identities, such as tan(π/12)\tan(\pi/12), greatly simplifies solving problems involving inverse functions.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Inverse Trigonometric Functions
Angle Subtraction Identities

Formulas

tan(a - b) = (tan(a) - tan(b)) / (1 + tan(a)tan(b))
tan(π/12) = tan(π/4 - π/3)

Theorems

Inverse Trigonometric Properties
Tangent Subtraction Formula

Suitable Grade Level

Grades 10-12