Question

Докажите тождество Cos(7π|2+α)*tg (π|2-α)-sin⁡〖(π|2-α)〗+ ctg (3π|2-α)= tgα

Answer 1

7p/2=3p+p/2=2p+p+p/2 
3p/2= p+p/2
cos(2p+p+p/2+a)=cos(p+p/2+a)=-cos(p/2+a)=sina
tg(p/2-a)=ctga=cosa/sina
sina*ctga=cosa
sin(p/2-a)=cosa
ctg(p+p/2-a)=ctg(p/2-a)=tga
решим
cosa-cosa+tga=tga  вот и все