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if veca, vecb and vecc are there mutuall...

if `veca, vecb and vecc` are there mutually perpendicular unit vectors and `veca` ia a unit vector then find the value of ` |2veca+ vecb + vecc |^2`

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`|veca+vecb+vecc+vecd|^(2)=sum|veca|^(2)+2sumveca.vecb=4+2vecd.(veca+vecb+vecc) " " (veca,vecb,vecc "are mutually perpendicular")`
`Let vecd=lambdaveca+muvecb+v vecc. Then vecd.veca=vecd.vecb=vecd.vecc=costheta`Therefore,
`lambda=mu=v=costheta`
` lambda^(2)+mu^(2)+v^(2)=1Rightarrow3cos^(2)theta=1costheta=1/sqrt3`
`|veca+vecb+vecc+vecd|^(2)=4+-(2.3)/sqrt3=4+-2sqrt3`
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