Ответы и объяснения

2012-09-27T18:49:03+04:00
2012-09-27T18:55:17+04:00

если я правильно поняла то пример вот такой:\sqrt{\frac{1-cosa}{1+cosa}}+\sqrt{\frac{1+cosa}{1-cosa}}=

=\sqrt{tg^2(\frac{a}{2})}+\sqrt{ctg^2(\frac{a}{2})}=tg(\frac{a}{2})+ctg(\frac{a}{2})=

=\frac{sin(\frac{a}{2})}{cos(\frac{a}{2})}+\frac{cos(\frac{a}{2})}{sin(\frac{a}{2})}=\\ =\frac{sin:2(\frac{a}{2})+cos^2(\frac{a}{2})}{cos(\frac{a}{2})sin(\frac{a}{2})}=

=\frac{1}{cos(\frac{a}{2})sin(\frac{a}{2})}=\frac{2}{sina}