[tex] \frac{sina+cosa}{sina-cosa} = \frac{ (sina+cosa)^{2} }{sin^{2}a-cos^{2}a} = \frac{sin^{2}a+cos^{2}a+2sinacosa}{-(cos^{2}a-sin^{2}a)} [/tex]
Utilizand formulele trigonometrice vei obtine:
[tex] \frac{1+sin2a}{-cos2a }=\frac{1+sin2a}{- \sqrt{1-sin^{2}2a} } = \frac{1+sin2a}{-( \sqrt{1+sin2a} )( \sqrt{1-sin2a} )} =- \frac{ \sqrt{1+sin2a} }{ \sqrt{1-sin2a} }[/tex]
[tex]=- \sqrt{ \frac{2-1+sin2a}{1-sin2a} } = \sqrt{ \frac{2}{1-sin2a}-1 } [/tex]
