Jawabanmu

2014-02-24T17:04:33+07:00
|r _{N} | =  \sqrt { i_{N}^2 +    j_{N}^2 }

*r_{N2} - r_{N1} = (4i+5j)-(1i+1j)
 r_{N2} - r_{N1} = 3i+4j

|r _{N} | =  \sqrt { 3^2 + 4^2 } = ......