Quick Help with Tangent Sum Formula: Solving for Tan 15 and Tan 30

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Discussion Overview

The discussion revolves around the application of the tangent sum formula in trigonometry, specifically focusing on calculating the values of Tan 15 and Tan 30. Participants are exploring the correct application of the formula and the resulting values.

Discussion Character

  • Technical explanation, Debate/contested, Homework-related

Main Points Raised

  • One participant presents a problem involving the tangent sum formula and expresses confusion about obtaining the correct answer.
  • Another participant asserts that the expression simplifies to Tan(45), which equals 1, suggesting the original answer provided is incorrect.
  • A third participant agrees with the second, reinforcing that the answer should be 1 and suggesting a reverse application of the formula.
  • A later reply acknowledges a possible misprint in the source material, indicating a shift in understanding.

Areas of Agreement / Disagreement

There is disagreement regarding the correct answer to the tangent sum problem, with some participants asserting the answer is 1, while the original poster believed it to be -1. The discussion remains unresolved regarding the correctness of the original answer.

Contextual Notes

Participants do not clarify the exact values of Tan 15 and Tan 30, nor do they resolve the implications of the tangent sum formula in this context. There are also no explicit definitions provided for the terms used.

CINA
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Hi, I'm studying for my pre-calc test tomorrow and I've run into a snag. I just can't seem to get the correct answer for a Tangent sum problem, and I'm hoping someone could help me out with it. It goes like this:

Sum Formula for Tangant: Tan (a+b) = Tan a + Tan b/1-Tan a * Tan b

Problem: Find the exact value,
Tan 15 + Tan 30/1- Tan 15 * Tan 30

Correct answer: -1

but I can't seem to get the answer in the end; are the tangants in the numerator added to make tan 45 then solved for? If not, how would you express tan 15 in an exact form? Similarly, how do you multiply tan 15 and tan 30? Or am I missing some other identity?

Its been driving me crazy all day!:cry:
 
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(Tan 15 + Tan 30) / (1- Tan 15 * Tan 30) =
Tan(15+30) =
Tan(45) =
1

The answer you have is wrong.
 
I don't think that's the correct answer. It should be 1. Just apply the formula backwards to get it.
 
Huh, that's quite odd... misprint in the book I suppose. Heh, it makes more sense now, thanks!
 

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