Asking for a value of trigonometri

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Discussion Overview

The discussion revolves around finding the value of the expression sin(180 - theta/2). Participants explore trigonometric identities and relationships to derive this value, with a focus on the application of sine and cosine functions.

Discussion Character

  • Mathematical reasoning

Main Points Raised

  • One participant asks for the value of sin(180 - theta/2), indicating a need for clarification on this trigonometric expression.
  • Another participant suggests using the identity sin(A - B) = sin(A)cos(B) - cos(A)sin(B) as a potential approach to solve the problem.
  • A different participant proposes using the identity sin(A + B) = sin(A)cos(B) + cos(A)sin(B) and notes the values of sin(180) and cos(180), assuming the angle is in degrees.
  • One participant acknowledges the need to substitute the known values of sin(180) and cos(180) into the expression, indicating a collaborative effort to clarify the problem.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the final expression or value, and the discussion includes multiple approaches and identities without resolving which is the most appropriate for the problem.

Contextual Notes

There is an assumption that the angle is measured in degrees, but this is not explicitly confirmed. Additionally, the desired form of the answer as a function of theta is not clearly defined by the original poster.

Sanosuke Sagara
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I want to ask for what is the value for sin (180-theta/2) ?Thanks for anybody that spend time looking on my problem.
 
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Use the fact that sin (A - B) = sin Acos B - cos Asin B.
 
Well, first use the fact that sin(A+B)= sin(A)cos(B)+ cos(A)sin(B)!

And, of course, sin(180)= 0 while cos(180)= -1 (I assume this is in degrees- you didn't actually say so).

If you want this as a function of theta only (again, you didn't say what you really wanted), you will also need to know that sin(theta/2)= +/- √((1/2)(1- cos(theta)).
 
Yeah, sorry that's what I meant :smile:. I thought it was obvious to then plug in the values of sin 180 and cos 180.
 

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