��.673 �� 9 �� (��)

�� #1

�� 673. ��. �� :�) 1+ cos �=2cos^2�/2�) 1- cos �=2sin^2 �/2�)(2 sin �-sin 2�)/(2 sin �+sin 2� )=tg^2�/2�)(1+sin 2�)/cos 2� =tg...

�� #2

�� 673. ��. �� :�) 1+ cos �=2cos^2�/2�) 1- cos �=2sin^2 �/2�)(2 sin �-sin 2�)/(2 sin �+sin 2� )=tg^2�/2�)(1+sin 2�)/cos 2� =tg...

�� , �� 9 ��, ��:

673. ��. �� :

�) 1+ cos �=2cos^2�/2

�) 1- cos �=2sin^2 �/2

�)(2 sin �-sin 2�)/(2 sin �+sin 2� )=tg^2�/2

�)(1+sin 2�)/cos 2� =tg (��/4+�)

�) tg �/2/(1+tg �/2)+tg �/2/(1-tg �/2)=tg �

�) 1/(1-tg �/2)-1/(1+tg �/2)=tg �

�) (2 tg �/2)/(1-tg^2 �/2)=tg �

�) (ctg �/2-tg �/2)/(�tg �/2+tg �/2)=cos�

*�� .

�� 9 ��

(�� )

��, ��, ��

�� Enjoy English 9 ��

��, ��, ��

(�� )

��, ��, ��

��, ��, ��

*�� , ��