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Question-192704




Question Number 192704 by Mingma last updated on 25/May/23
Answered by HeferH last updated on 25/May/23
Commented by HeferH last updated on 25/May/23
12+12(√3)−x =24   x=12((√3)−1)   shaded = ((12((√3)−1)∙6)/2) = 36((√3)−1) u^2
$$\mathrm{12}+\mathrm{12}\sqrt{\mathrm{3}}−{x}\:=\mathrm{24} \\ $$$$\:{x}=\mathrm{12}\left(\sqrt{\mathrm{3}}−\mathrm{1}\right) \\ $$$$\:{shaded}\:=\:\frac{\mathrm{12}\left(\sqrt{\mathrm{3}}−\mathrm{1}\right)\centerdot\mathrm{6}}{\mathrm{2}}\:=\:\mathrm{36}\left(\sqrt{\mathrm{3}}−\mathrm{1}\right)\:{u}^{\mathrm{2}} \\ $$
Commented by Mingma last updated on 25/May/23
Perfect ��
Answered by MM42 last updated on 25/May/23
BC=24sin15  &  <BCD=105^0     △BCD  : ((12)/(sin105)) =((24sin15)/(sinD))   ⇒sinD=2sin105sin15=2cos15sin15=(1/2)⇒<D=30^0  ⇒<CBD=45^0   ⇒S_(BCD) =(1/2)×12×24×sin15×sin45=36((√3)−1) ✓
$${BC}=\mathrm{24}{sin}\mathrm{15}\:\:\&\:\:<{BCD}=\mathrm{105}^{\mathrm{0}} \:\: \\ $$$$\bigtriangleup{BCD}\:\::\:\frac{\mathrm{12}}{{sin}\mathrm{105}}\:=\frac{\mathrm{24}{sin}\mathrm{15}}{{sinD}}\: \\ $$$$\Rightarrow{sinD}=\mathrm{2}{sin}\mathrm{105}{sin}\mathrm{15}=\mathrm{2}{cos}\mathrm{15}{sin}\mathrm{15}=\frac{\mathrm{1}}{\mathrm{2}}\Rightarrow<{D}=\mathrm{30}^{\mathrm{0}} \:\Rightarrow<{CBD}=\mathrm{45}^{\mathrm{0}} \\ $$$$\Rightarrow{S}_{{BCD}} =\frac{\mathrm{1}}{\mathrm{2}}×\mathrm{12}×\mathrm{24}×{sin}\mathrm{15}×{sin}\mathrm{45}=\mathrm{36}\left(\sqrt{\mathrm{3}}−\mathrm{1}\right)\:\checkmark \\ $$
Commented by MM42 last updated on 25/May/23
Commented by Mingma last updated on 25/May/23
Perfect ��

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