Question

please answer 29 number

Answer 1

as the 2 vectors are perpendicular to each other... so angle is 90°
______________________________

so as they are perpendicular their dot product must be 0
as A.B =ABcos(90) =0
{as we know that cos90°=0}
______________________________

=>(2i+3j+8k).(4j-4i+α k) =0

=>(2i+3j+8k).(-4i+4j+α k) =0

=>(2)(-4) +(3)(4)+8(α) =0

=>-8+12+8α =0

=>4+8α=0

=>8α = -4

=>α =-4/8 = -1/2
______________________________

hope it helps you...
☺☺