Question

a) tg25+tg35=

б)tg п/5 - tg п/10=

Answer 1

a) tgx+tgy=sin(x+y)/cosxcosy
=sin60/cos25cos35=(√3/2)/1/2(cos60+cos10)=2√3/(1+2cos10)
б)=sin(П/5-п/10)/cosП/5cosП/10=(sinП/10)/(cosП/10cosп/5)=
=2sin^2(П/10)/(2cosп/10sinп/10)cosп/5=4sin^2(П/10)/sin(2П/5)=
=4sin^2(П/10)/sin(П/2-П/10)=4sinП/10*tgп/10