做PE丄AB于E,则EAO=m1,PAE=m,PE丄POE
在PAO中P0丄AO 则cosPAO=cosm2=AO/PA;
PE丄POE,则AE丄PE,AE丄OE
在PAE中AE丄PE 则cosPAE=cosm=AE/PA;
同理在OAE cosOAE=cosm1=AE/OA;
COSm1*cosm2=(AE/OA )*(AO/PA)=cosm
做PE丄AB于E,则EAO=m1,PAE=m,PE丄POE
在PAO中P0丄AO 则cosPAO=cosm2=AO/PA;
PE丄POE,则AE丄PE,AE丄OE
在PAE中AE丄PE 则cosPAE=cosm=AE/PA;
同理在OAE cosOAE=cosm1=AE/OA;
COSm1*cosm2=(AE/OA )*(AO/PA)=cosm