Prove that `[axxb, a xx c, d] = (a*d)[a, b, c]`

If a, b, c and d are four coplanr points, then prove that [a b c]=[b c d]+[a b d]+[c a d] .

If a, b, c and d are four coplanr points, then prove that [a b c]=[b c d]+[a b d]+[c a d] .

If a, b, c and d are four coplanr points, then prove that [a b c]=[b c d]+[a b d]+[c a d] .

If a ,b,c , d are in G.P. prove that (b + c)(b + d) = (c + a)(c+d)

Let R be a relation on N xx N defined by (a,b) R(c, d) hArr a + d= b + c for all (a,b) (c,d) in N xx N show that, (a,b) R (c, d) rArr (c, d) R (a, b) for all (a, b) (c, d) in N xx N

Value of [vec a xx vec b,vec a xx vecc,vec d] is always equal to (a) ( ⃗ a . ⃗ d ) [ ⃗ a ⃗ b ⃗ c ] (b) ( ⃗ a . ⃗ c ) [ ⃗ a ⃗ b ⃗ d ] (c) ( ⃗ a . ⃗ b ) [ ⃗ a ⃗ b ⃗ d ] (d) none of these

If a : b = c : d , then prove that (a + c) : (b + d) = sqrt(a^(2) - c^(2)) : sqrt(b^(2) - d^(2))