1.

Let `(veca (x) = (sin x) hati+ (cos x) hatj and vecb(x) = (cos 2x) hati + (sin 2x) hatj` be two variable vectors `( x in R)`. Then `veca (x) and vecb (x) ` areA. collinear for unique value of xB. perpendicular for infinte values of x.C. zero vectors for unique value of xD. none of these

Answer» Correct Answer - b
if `veca ( x) and vecb are bot, "then" veca. Vecb =0`
`Rightarrow sin x cos 2x + cos x sin 2x =0`
`sin (3x) =0 = sin 0 `
` 3x = npi 0or x = (npi)/3`
therefore, the two vectors are `bot` for infinite values.


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