| > @ƒ¿(ƒÎ/10) ‚Ì‚Æ‚«AŽŸ‚Ì“™Ž®‚ðØ–¾‚µAsin(ƒÎ/10) ‚Ì’l‚ð‹‚ß‚æB > @(1) sin 2ƒ¿ cos 3ƒ¿
¶•Ó=sin 2ƒ¿=sin 2ƒÎ/10=sin (-3ƒÎ/10+ƒÎ/2)=cos(-3ƒÎ/10)=cos(3ƒÎ/10)=cos 3ƒ¿=‰E•Ó // > @(2) 2sinƒ¿ 4cos^2 (ƒ¿|3) ‚Å‚Í‚È‚A2sinƒ¿=(4cos^2 (ƒ¿)|3) ‚Å‚·‚ËB
—¼•Ó‚Écosƒ¿‚ðŠ|‚¯‡‚킹‚éB @2sinƒ¿cosƒ¿ (4cos^2 (ƒ¿)|3)cosƒ¿ ¨2sinƒ¿cosƒ¿=sin2ƒ¿=cos3ƒ¿=cos(ƒ¿+2ƒ¿)=cosƒ¿cos2ƒ¿-sinƒ¿sin2ƒ¿ ={cos2ƒ¿-2sin^2(ƒ¿)}cosƒ¿={(2cos^2ƒ¿-1)-2(1-cos^2(ƒ¿))}cosƒ¿ =(4cos^2 (ƒ¿)|3)cosƒ¿@@@di0j
(0)Ž®‚Ì—¼•Ó‚ðcosƒ¿‚ÅŠ„‚ê‚Î 2sinƒ¿=(4cos^2 (ƒ¿)|3)@@ˆ¶•Ó=‰E•Ó //
2sinƒ¿=(4cos^2 (ƒ¿)|3)=(4(1-sin^2 (ƒ¿))|3)=1-4sin^2 (ƒ¿) ˆ4sin^2(ƒ¿)-2sinƒ¿-1=0 ‰ð‚ÌŒöŽ®‚Æ(sinƒ¿>0)‚æ‚èAsinƒ¿=(1+ã5)/4
|