If vector ` vec b=(t a nalpha,-1,2sqrt(sinalpha//2))a n d vec c=(t a nalpha, t a nalpha, -3/(sqrt(sinalpha//2)))` are orthogonal and vector ` vec a=(1,3,sin2alpha)` makes an obtuse angle with the z-axis, then the value of `alpha` is `a. alpha=(4n+1)pi+tan^(-1)2` `b. alpha=(4n+1)pi-tan^(-1)2` `c. alpha=(4n+2)pi+tan^(-1)2` `d. alpha=(4n+2)pi-tan^(-1)2`

Options

A. `alpha =(4n+1)pi -tan^(-1)2`
B. `alpha =(4n+2)pi - tan^(-)2`
C. `alpha =(4n-1)pi + tan^(-1)2`
D. `alpha (4n-2)pi - tan^(-1)2`

Answer

A, B