如图所示,在三角形ABC中,角A=90度,P是AC中点,PD垂直BC,D为垂足,BC等于9,DC等于3,求AB的长

PC*COS角C=CD=3
BC*COS角C=9*COS角C=AC=2PC=2*3/COS角C
=>(COS角C)^2=6/9
=>(SIN角C)^2=1/3
=>AB=BC*SIN角C=9*(根号3/3)=3*根号3