सिद्ध कीजिए कि सदिश ` hati + 2 hatj + 5 hatk ` और ` hati - 2 hatj + hatk` एकसंतलीय है ।

Explanation

माना ` veca = hati + 2 hatj + 5 hatk`,
` vecb = hati - hatj + 2 hatk , vec c = hati - 2 hatj + a hatk `
अब ` [ veca " " vecb" " vecc] =|{:( 1,2,5) ,( 1,-1,2) ,( 1,-2,1):}|`
` = 1 ( -1 + 4 ) - 2( 1-2) +5 ( -2 +1)`
` = 3 + 2 - 5 =0`
`: ' [ vec a " " vecb " " vecc ] =0`
अंत : सदिश ` veca , vecb , vecc`एकसंतलीय है ।