minta tolong bos no 8,9,10 pliss

8.) 2 sin A cos A / 1 + cos^2A - sin^2A
= 2sinA cos A / ( cos^2a + sin^2a ) + cos^2a - sin^2a
=2sinA cos A  / 2 cos^2a
= sin A / cos A
= Tan A ( B )
9. ) 1 - sin a + 1 + sin a / ( 1 + sin a ) ( 1 - sin a )
     = 2 / 1 - sin^2a
     = 1 / ( cos^2a + sin^2a ) - sin^2a
     = 2 / cos^2a
     = 2 sec^2a ( A )
10. ) sin c / ( 1 + cos C ) + sin C / ( 1 - cos C )
       = ( sin C ( 1 - cos C ) + sin C ( 1 + cos C ) / ( 1 + cos C ) ( 1 - cos C )
       = ( sin C - sinccosc + sin C + sinccosc ) / ( 1 - cos^2C )
       = (2sin C ) / ( sin^2c )
       = 2 / sin C
       = 2 cosec C ( B )


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