著者:マスオ
発売日:2016/01/14
出版社:SBクリエイティブ
ISBN:4797385588
${\rm sin}15^\circ=\dfrac{\sqrt{6}-\sqrt{2}}{4}\\{\rm cos}15^\circ=\dfrac{\sqrt{6}+\sqrt{2}}{4}\\ {\rm tan}15^\circ=\dfrac{\sqrt{6}-\sqrt{2}}{\sqrt{6}+\sqrt{2}}=2-\sqrt{3}$ $\sin18^{\circ}=\dfrac{\sqrt{5}-1}{4}$