maple homework

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!

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.

Quote:

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Originally Posted by dsheller

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.

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

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