[Math4u] Re: trig function value

I don't think anyone actually ever responded to this question.
Excepting the character set issue, the problem is

find the exact value:

( tan(5pi/4) - tan(pi/12) ) / ( 1 + tan(5pi/4)tan(pi/12) )

This looks suspiciously like the difference identity for tangent:

tan(A - B) = ( tanA - tanB ) / ( 1 + tanAtanB )

so

( tan(5pi/4) - tan(pi/12) ) / ( 1 + tan(5pi/4)tan(pi/12) )

= tan(5pi/4 - pi/12)
= tan(7pi/6)
= tan(pi/6)
= sqrt(3)/3

-- Rick

--- In Math4u@yahoogroups.com, tanisha branch <mindlesspoet89@...> wrote:
>
> find the exact value:
>
> tan(5é/4) – tan(é/12)
> 1+tan(5é/4)tan(é/12)
>
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