If `vecA, vecB` are perpendicular vectors
`:' vecA = 5 hati + 7 hatj - 3 hatk`
`:'vecB = 2 hati + 2 hatj - c hatk` . Value of c is

Options

A. -2
B. 8
C. -7
D. -8

Explanation

`v^2-u^2=2g h`
`v^2=2g h" "( :'u=0)`
Let, `v_1=2v`,when `h=x`
`2g x=(2v)^2=4v_2`
`implies2g x=4(2g h) ( :'v=sqrt(2gh))`
`:.x=4 h`
` "Further distance"=4 h-h=3 h`