Finding Four Angles Using the Cosine Double Angle Formula

  • Context: High School 
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Discussion Overview

The discussion revolves around finding four angles based on the cosine double angle formula, specifically the equation cos2x = 2 cos x sin x. The scope includes mathematical reasoning and problem-solving within a specified range of angles.

Discussion Character

  • Mathematical reasoning, Homework-related

Main Points Raised

  • One participant requests assistance in finding four angles for the equation cos2x = 2 cos x sin x.
  • Another participant asks for clarification on the range of x and references a previous discussion on the topic.
  • A participant specifies the range of x as 0 to 360 degrees.
  • One participant suggests that the problem is easily solvable by recalling two trigonometric identities related to sine and tangent.
  • A later reply claims success in solving the problem.

Areas of Agreement / Disagreement

The discussion does not reach a consensus, as participants express varying levels of understanding and approaches to the problem.

Contextual Notes

Limitations include the need for clarification on assumptions regarding the identities used and the specific methods for solving the equation.

Maria
Can someone please help me with this one?

cos2x = 2 cos x sin x

I need to find 4 angles :rolleyes:
 
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Within what range of x? And have you checked what I posted to this problem in the other thread?
 
within the range of 0, 360
 
Well this is easily solvable as long as you remember these 2 identities:

[tex]\sin 2 \theta \equiv 2 \cos \theta \sin \theta[/tex]

and:

[tex]\tan \theta \equiv \frac{\sin \theta}{\cos \theta}[/tex]
 
I got it right... :smile:
 

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