Question

15 балов!!! Номер 1!!

Answer 1

1
$cos105=cos(90+15)=-sin15=- sqrt{(1-cos30)/2} =- sqrt{2- sqrt{3} } /2$
2
$sin13 pi /12=sin( pi + pi /12)=-sin pi /12=- sqrt{(1-cos pi p/6)/2} =$$- sqrt{2- sqrt{3}} /2$
3
$tg15=sin15/cos15= sqrt{(2- sqrt{3})/(2+ sqrt{3} ) }$
4
$ctg5 pi /12=tg pi /12= sqrt{(2- sqrt{3} )/(2+ sqrt{3}) }$