Buktikan tan A cos A=sin A!!

[tex] \tan \: a \: = \frac{ \sin \: a}{ \cos \: a} \\ \frac{ \sin \: a}{ \cos \: a} \times \cos \: a \: = \sin \: a[/tex]

[tex] \tan(a) = \frac{ \sin(a) }{ \cos(a) } [/tex]
Sehingga
[tex] \tan(a) \cos(a) = \sin(a) \\ \frac{ \sin(a) }{ \cos(a) } \times \cos(a) = \sin(a) \\ \frac{ \sin(a) \cos(a) }{ \cos(a) } = \sin(a) \\ \sin(a) = \sin(a) [/tex]
Terbukti !!!
Semoga dapat dipahami