11/05/04 21:09:30.05 lEFXU9rF0
>>361
面倒くさいから→を省略するけど、
a・b=(OM+MA)・(OM+MB)={1/2(a+b)-1/2(a-b)}・{1/2(a+b)+1/2(a-b)}
=1/4|a+b|^2-1/4|a-b|^2={1/2|a+b|}^2-(1/2|a-b|}^2=OM^2-(1/2AB)^2
11/05/04 21:09:30.05 lEFXU9rF0
>>361
面倒くさいから→を省略するけど、
a・b=(OM+MA)・(OM+MB)={1/2(a+b)-1/2(a-b)}・{1/2(a+b)+1/2(a-b)}
=1/4|a+b|^2-1/4|a-b|^2={1/2|a+b|}^2-(1/2|a-b|}^2=OM^2-(1/2AB)^2