यदि सदिश `bara` और `barb` परस्पर लंबवत हों, तो सिद्ध कीजिए कि
`(bara+barb)^(2)=(bara-barb)^(2).`

bara.(barb+barc)xx(bara+barb+barc)=

(bara+barb).(barb+barc)xx(bara+barb+barc)=

(bara+barb).(barb+barc)xx(bara+barb+barc)=

[bara barb barc]+[bara barc barb] =

(bara+2barb-barc).(bara-barb)xx(bara-barb-barc)=

[[bara-barb, barb-bara, barc-bara]]=

The vectors bara,barb and bara+barb are

The vectors bara,barb and bara+barb are

prove that: (baraxxbarb) ^ 2 = | bara | ^ 2 | barb | ^ 2 - (bara.barb) ^ 2 = | (bara.bara, bara.barb), (bara.barb, barb.barb) |