∵∠A比∠B比∠C＝1比5比6∴∠A=15°，∠B=75°，∠C=90°∵斜边AB上的中线=3∴斜边AB=3×2=6∴令AB中点为D则CD=BD=3S△BCD=1/2*BD*CD*sin∠BDC=1/2×3×3×sin30° = 9/4S△ABC = 2S△BCD = 9/2 = 4.5
