Докажите тождество: (SIN2a+SIN6a)/(COS2a+COS6a)=TG4a.

Question

Докажите тождество:

(SIN2a+SIN6a)/(COS2a+COS6a)=TG4a.

Answer 1

(SIN2a+SIN6a)/(COS2a+COS6a)=2SIN4a*COS2a/2COS4a*COS2a=SIN4a/COS4a=TG4a