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Question Number 176468 by blackmamba last updated on 20/Sep/22
sin(2x+18°)sin(2x+12°)=sin36°sin48° tan2x=tanM.tanN 0°<M,N<90°⇒M+N=?°
Commented byPeace last updated on 20/Sep/22
istartedWithe48,iseenoniceForm 24istheRightithink
Answered by Peace last updated on 20/Sep/22
sin(2x)cos(18)+cos(2x)sin(18)sin(2x)cos(12)+cos(2x)sin(12)=sin(2.18)sin(2.12) ⇔tg(2x)cos(18)+sin(18)tg(2x)cos(12)+sin(12)=sin(36)sin(24)= t=tg(2x) ⇔tg(2x)+tg(18)tg(2x)+tg(12)=cos(12)cos(18).sin(36)sin(48)=sin(36)cos2(12)cos2(18)sin(24) =2sin(18)cos(18)cos2(12)cos2(18).2sin(24)cos(24) =tg(18)cos2(12)2sin(12)cos(12)=tg(18)tg(12) t+tg(18)t+tg(12)=c⇒t(1−c)=ctg(12)−tg(18)⇒tg(2x)=ctg(12)−tg(18)c−1 tg(18)tg(12)−tg(18)1−tg(18)tg(12)=tg(18)(tg(12−tg(18))tg(12)−tg(18).tg(12) =tg(18)tg(12) M+N=30
Commented byblackmamba last updated on 26/Sep/22
wrong
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