maple homework

[dsheller]

Well, we are given maple homeworks to do and I can't seem to get a couple of them right:

Find two unit vectors orthogonal to both a= [9, 15, -2] and b = [17, 19, -10]. Assign your answers to ans1 and ans2.

The next one seems like it would be pretty easy, I get an answer of 72 whatever units ^2, but that is wrong =/

Find the area of the parallelogram with vertices A = [9, 5, 5], B = [-9, 18, 3], C = [-1, 20, 5], and E = [1, 3, 3]. Assign your answer for the area to ans1.

Basically what I did was go through and plotted them with pointplot3d and then realized it was a square, so i just found distance of each length and found area... didn't work =/

Any help would be great, thanks!

[dsheller]

Duh, solved the first one, just the cross product of the two vectors and then the negative of that... still out on the second one though.

[TBeck]

Find the area of the parallelogram with vertices A = [9, 5, 5], B = [-9, 18, 3], C = [-1, 20, 5], and E = [1, 3, 3]. Assign your answer for the area to ans1.

using the magnitude of the cross product
http://en.wikipedia.org/wiki/Cross_product#Properties

[dsheller]

Yea I got it last night, just had to figure out what vectors to use as to avoid the diagonal. Thank you though.