Question

demostrar
$1 - sin \alpha \times cos \alpha \times \tan\alpha = \cos ^{2} \alpha$
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Answer 1

$1 - \sin( \alpha ) \times \cos( \alpha ) \times \tan( \alpha ) = { \cos }^{2} \alpha$

$1 - \sin( \alpha ) \times \cos( \alpha ) \times \frac{ \sin( \alpha ) }{ \cos( \alpha ) } = { \cos }^{2} \alpha$

$1 - \sin( \alpha ) \times \sin( \alpha ) = { \cos }^{2} \alpha$

$1 - { \sin }^{2} \alpha = { \cos }^{2} \alpha$

${ \cos }^{2} \alpha = { \cos}^{2} \alpha$