Previous | Next --- Slide 7 of 52
Back to Lecture Thumbnails
lizard

What's the geometric reasoning behind e1, e2, and e3 being the first row of the matrix?

goldfish

Is the 2d cross product just used as a shortcut to get the area of the parallelogram?

lights

@lizard e1,e2,e3 are the vectors like x,y,z. It helps to denote the values in each axis for the resultant cross product vector.

yeeEeEet

why does the 2d cross product produce a scalar

nivek

u x v in the 2D sense seems to correspond to: det[-u-] [-v-]

Like goldfish I wonder what the application for this is.

samalex

@yeeEeEet I guess the cross product is only defined for 3d, so a 2d vector is appended with 0s. So the result is also 3d with the last element non-zero.

stroucki

The sqrt(det(...)) mumble really comes down to the magnitude of the cross product vector, according to wikipedia. And are the u, v and u x v arranged as row vectors for finding the determinant?