- #1

nobodyuknow

- 64

- 0

## Homework Statement

http://prntscr.com/p7dxt

Here's a screenshot of the revision question.

## Homework Equations

## The Attempt at a Solution

Co-ordinates of each point

A, (0, 60, 0)

B, (40, 0, 0)

C, (-40, 0, 40)

D, (-60, 0, -60)

Position Vectors

rAB, 40i + -60j + 0k

rAC, -40i + -60j + 40k

rAD, -60i + -60j + -60k

Unit Vectors corresponding these position vectors

eAB, 0.5547i + -0.8321j + 0k

eAC, -0.4851i + -0.7276j + 0.4851k

eAD, -0.5774i + -0.5774j + -0.5774k

This is all I know, I'm not sure how to complete the other questions.

For question

**would I have to put the two position vectors and do a cross product?**

Something like...

i j k

-0.4851 -0.7276 0.4851

-0.5774 -0.5774 -0.5774

[(-0.7276)(-0.5774) - (0.4851)(-0.5774)]i + [(-0.4851)(-0.5774) - (0.4851)(-0.5774)]j + [(-0.4851)(-0.5774) - (-0.7276)(-0.5774)]k

If not, I'm totally lost, and need help!

Something like...

i j k

-0.4851 -0.7276 0.4851

-0.5774 -0.5774 -0.5774

[(-0.7276)(-0.5774) - (0.4851)(-0.5774)]i + [(-0.4851)(-0.5774) - (0.4851)(-0.5774)]j + [(-0.4851)(-0.5774) - (-0.7276)(-0.5774)]k

If not, I'm totally lost, and need help!

Last edited: