Prove that : `tan\ pi/7*tan\ (2pi)/7*tan\ (3pi)/7=sqrt(7)`

Show that: (tan^2\ pi/7+tan^2\ (2pi)/7+tan^2\ (3pi)/7)(cot^2\ pi/7 +cot^2\ (2pi)/7+ cot^2\ (3pi)/7)=105

Prove that : cos(pi/7)cos((2pi)/7) cos((3pi)/7)=1/8

Prove that tan(pi/16)+2tan(pi/8)+4=cot (pi/16) .

Prove that tan(pi/16)+2tan(pi/8)+4=cot(pi/6) .

The value of (1+tan\ (3pi)/8*tan\ pi/8)+(1+tan\ (5pi)/8*tan\ (3pi)/8)+(1+tan\ (7pi)/8*tan\ (5pi)/8)+(1+tan\ (9pi)/8* tan\ (7pi)/8)

Prove that: (tan(pi/4+A)+tan(pi/4-A))/(tan(pi/4+A)-tan(pi/4-A))="cosec"2A

Prove that: sin ((pi)/(7))+sin((2pi)/(7)) + sin((8pi)/(7)) + sin((9pi)/(7))=0

Prove that: tan(pi/4+A). Tan((3pi)/4)+A=-1

Prove that: cos(pi/7)cos((2pi)/7)cos((4pi)/7)=-1/8

Prove that : tan^(-1)2+tan^(-1)3=(3pi)/4