Question

Find a vector c = (c1, c2, c3) which is orthogonal to both a = (-4,4,2) and b = (2, -6, 9) and such that c1 =-4

Answer 1

Find a vector c = (c1, c2, c3) which is orthogonal to both a = (-4,4,2) and b = (2, -6, 9) and such that c1 = -4

Alright, so I did the cross product of a x b and it came out to be 48i + 44j +16k, which is wrong if they want c1 to = -4

figured you could scale it down by dividing the component form until i = 4, then just multiply it all by a negative so that the scaled down orthogonal vector would just be going in the opposite direction. but, the program we use to enter our answers doesn't like that answer (-4i - 11/3j - 4/3k)

Answer 2

i think that you did it all properly, just a small mistake with the cross product, it is (48,40,16) and the scaled vector will be (-4, -10/3,-4/3)

Answer 3

ahhh sweet
thank you so much.. only had 3 shots at it and that was my last try

Answer 4

success

Answer 5

i just learned this recently, and used wolfram alpha to check my results... :)