Wednesday, February 6, 2013

How to verify this identity?sin x + tan x/ 1 + sec x = sin x thank you very much!

We need to prove that :


sinx+
tanx / (1+ sec x ) = sinx


We will start from the left
side.


(sinx + tanx)/ (1+
secx)


We know that tanx = sinx/cosx ans secx =
1/cosx.


Then, we will substitute with
identities.


==> (sinx+ sinx/cosx) / (1+
1/cosx)


==> [(sinx*cosx + sinx)/cosx] / [ ( cosx +
1)/cosx]


Reduce
cosx.


==> (sinxcosx + sinx ) / (cosx +
1)


Now we will factor sinx from the
numerator.


==>
sinx*(cosx+1)/(cosx+1)


Now we will reduce
cosx+1


==>
sinx


Then we proved that (
sinx+tanx)/(1+secx) = sinx.

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