B
åå«è®¾AO=x,BO=y,CO=m,DO=n,
â AOB=α â AOD=β,å
¶ä¸Î²ï¼Ïï¼Î±
sinβ=sinα
(1/2)XYsinα=4
(1/2)mnsinα=9
(XY)/(mn)=4/9
sinα=26/(xy+mn)
Saob+Sboc+Scod+Saod
=13+(1/2)xnsinα+(1/2)mysinα
=13+(1/2)(xn+my)sinα
=13+(1/2)(xy)sinα[(n/y)+(m/x)]
>=13+4Ã2â[(mn)/(xy)]
ä¸å¼å½ä¸ä»
å½(n/y)ï¼(m/x)ï¼3/2åçå·
Saob+Sboc+Scod+Saodçæå°å¼ä¸º13ï¼12ï¼25
温馨提示:答案为网友推荐,仅供参考