Possible values of p for a triangle with given angle A=45 and tanBtanC=p

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Homework Help Overview

The problem involves determining possible values of \( p \) for angles \( A, B, C \) in a triangle, given that \( A = 45^\circ \) and \( \tan B \tan C = p \). The discussion centers on the relationship between the angles and the constraints imposed by the triangle's properties.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the expression for \( \cos(B-C) \) derived from the relationship between \( p \) and the angles. Questions arise regarding the independence of \( B-C \) from \( C \) and the implications of the angle ranges on the cosine function.

Discussion Status

The discussion is active, with participants exploring the implications of angle relationships and ranges. Some guidance has been provided regarding the constraints on \( C \) and how they affect the values of \( \cos(B-C) \).

Contextual Notes

It is noted that \( B + C = 135^\circ \), which influences the values that \( B \) and \( C \) can take within the context of a triangle.

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Homework Statement


Let A,B,C be three angles such that A=45 (degrees) and tanBtanC=p. Find all possible values of p such that A,B,C are the angles of a triangle.


Homework Equations





The Attempt at a Solution



I got an expression for cos(B-C)= (1+p)/{(p-1)√2}
My book says this-
Since B or C can vary from 0 to 135,
-1/√2 < (1+p)/{(p-1)√2} <= 1

I did not understand how this step came. Please help
 
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Hint: You know that B+C=135, so B=135-C and B-C=135-2C.
 
But B-C=135-2C is not independent of C.
How will that help?
 
Why should it be independent of C? Think about what range of values C can assume and what this means about range of values cos(B-C) can assume.
 
Thanks, I got it
 

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