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Trigonometry 9 Online
OpenStudy (anonymous):

Ok here it goes

OpenStudy (anonymous):

\[\tan x \sin x+ \cos x= \sec x\]

jhonyy9 (jhonyy9):

how can you rewrite tanx = ?

jhonyy9 (jhonyy9):

so tanx = sin x / cos x yes ?

OpenStudy (anonymous):

\[\frac{ \sin x }{ \cos x }\]

jhonyy9 (jhonyy9):

than substitute in place of tanx what will get ?

OpenStudy (anonymous):

cos x + cos x

jhonyy9 (jhonyy9):

no

jhonyy9 (jhonyy9):

check it please

OpenStudy (anonymous):

\[\frac{ \sin x }{ \cos x } \sin x + \cos x\]

OpenStudy (anonymous):

alryt looks like you guys gave up on me

jhonyy9 (jhonyy9):

yes but do you can continue it ?

OpenStudy (anonymous):

Should you cancel something here?

jhonyy9 (jhonyy9):

multiplie sin x *sin x = ?

jhonyy9 (jhonyy9):

so than what you get ?

jhonyy9 (jhonyy9):

will be sin^2 x / cos x y

jhonyy9 (jhonyy9):

yes ?

OpenStudy (anonymous):

Wait how was that?

jhonyy9 (jhonyy9):

so tanxsinx +cosx = secx because tanx = sinx / cos x sinx ---- *sinx +cosx = secx cosx sin^2 x ------ + cos x = sec x cos x yes ?

OpenStudy (johnweldon1993):

\[\large tan(x)sin(x) + cos(x) = sec(x)\] we know \(\large tan(x) = \frac{sin(x)}{cos(x)}\) so \[\large \frac{sin(x)}{cos(x)}\times sin(x) + cos(x) = sec(x)\] Multiply the sin/cos times sin \[\large \frac{sin^2(x)}{cos(x)} + cos(x) = sec(x)\] we need a common denominator to add those fractions...looks like cos(x) would be the best...so multiply the cos(x) by cos(x)/cos(x) \[\large \frac{sin^2(x)}{cos(x)} + \frac{cos^2(x)}{cos(x)} = sec(x)\] we can now place the fraations over the commondenominator \[\large \frac{sin^2(x) + cos^2(x)}{cos(x)} = sec(x)\] We know that \(\large sin^2(x) + cos^2(x) = 1 \) so \[\large \frac{1}{cos(x)} = sec(x)\] which is true...so the identity is verified

OpenStudy (anonymous):

oh thx

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