Find :

`( veca + vecb ). ( veca - vecb ) `
( A ) 1
( B ) 0
( C ) `a^2 + b^2`
( D ) `a^2 - b^2`

If veca_|_vecb and (veca+vecb)_|_(veca+mvecb) , then m= (A) -1 (B) 1 (C) (-1veca"^2)/(vecb|^2) (D) 0

If |veca|=4,|vecb|=2 and angle between veca and vecb is pi/6 then (vecaxxvecb)^2 is (A) 48 (B) (veca)^2 (C) 16 (D) 32

If |veca|=2,|vecb|=3 and |2veca-vecb|=5, then |2veca+vecb| equals: (A) 17 (B) 7 (C) 5 (D) 1

If the angle betweenteh unit vectors veca and vecb is vec60^0 then |veca-vecb| is (A) 0 (B) 1 (C) 2 (D) 4

The non zero vectors veca,vecb, and vecc are related byi veca=8vecb nd vecc=-7vecb. Then the angle between veca and vecc is (A) pi (B) 0 (C) pi/4 (D) pi/2

The vector (veca-vecb)xx(veca+vecb) is equal to (A) 1/2 (vecaxxvecb) (B) vecaxxvecb (C) 2(veca+vecb) (D) 2(vecaxxvecb)

If vecasxxvecb=0 and veca.vecb=0 then (A) veca_|_vecb (B) veca||vecb (C) veca=0 and vecb=0 (D) veca=0 or vecb=0

If veca,vecb,vecc are non coplanar vectors then ([veca+2vecb vecb+2cvecc vecc+2veca])/([veca vecb vecc])= (A) 3 (B) 9 (C) 8 (D) 6

If veca, vecb and vecc are vectors such that |veca|=3,|vecb|=4 and |vec|=5 and (veca+vecb) is perpendicular to vecc,(vecb+vecc) is perpendicular to veca and (vecc+veca) is perpendicular to vecb then |veca+vecb+vecc|= (A) 4sqrt(3) (B) 5sqrt(2) (C) 2 (D) 12

If veca and vecb are two unit vectors such that veca+2vecb and 5 veca-4vecb are perpendicular to each othre, then the angle beween veca and vecb is (A) 45^0 (B) 60^0 (C) cos^-1(1/30 (D) cos^-1(2/7)