Question

Cos9 + sin 9 / cos 9- sin9 = tan 54

Answer 1

Hi friend,

54°-9°=45°
or, 54°=45°+9°
or, tan54°=tan(45°+9°)
or, tan54°=tan45°+tan9°/1-tan45°tan9°
or, tan54°=1+tan9°/1-tan9° [∵, tan45°=1]
or, tan54°=(1+sin9°/cos9°)/(1-sin9°/cos9°)
or, tan54°={(cos9°+sin9°)/cos9°}/{(cos9°-sin9°)/cos9°}
or, tan54°=cos9°+sin9°/cos9°-sin9°

Hence,Proved....

HOPE THIS HELPS YOU:-))