圖畫得不太標(biāo)準(zhǔn).                               /    這邊是不用相似做的
不知道你學(xué)沒學(xué)相似三角形                        /∵AC=5  CE:AE=3:2 E在AC上
∵AC=5  CE:AE=3:2 E在AC上                    /∴CE=3 AE=2
∴CE=3 AE=2                                             /∵CD是直徑  C是弧ACB的中點(diǎn)
∵CD是直徑  C是弧ACB的中點(diǎn)                  我∴CD⊥AB CD平分AB 
∴CD⊥AB CD平分AB                                是  設(shè)AM=x  則CM=根號(hào)下(25-x²)
∵∠EAB+∠=90°=∠EAB+∠MCA              分  EM²=CM²-CE²=AM²-AE²
∴∠AME=∠MCA                                       割        25-x²-9=x²-4
又∵M(jìn)E⊥AC于點(diǎn)E                                     線           X=√10
∴∠AEM=∠MEC                                        /              AM=√10 
∴△AEM∽△MEC                                       /         AB=2AM=2√10
AE:EM=EM:CE                                             /
EM=√6  AM=√10                                          /
AB=2AM=2√10                                            /