Formula of shortest distance between two skewed lines

[gxc9800]

Homework Statement

kindly refer to the yellow highlighted part,
why is

but not

?

Homework Equations

The Attempt at a Solution

 

[HallsofIvy]

? The "yellowed part" says precisely the second: |AC|= |AB| cos(\theta)

 

[gxc9800]

? The "yellowed part" says precisely the second: |AC|= |AB| cos(\theta)

please refer to the lower part , it states that |AB|= |AB| cos(\theta)... after eliminate |vector b1 x vector b2|

 

[HallsofIvy]

No, there is nowhere, in what you posted, that says that.

 

[Mark44]

From https://www.physicsforums.com/threads/guidelines-for-students-and-helpers.686783/

5. Do not simply post images of the problem statement or your work. While posting images may be convenient for you, it's actually one of the most effective ways of getting your request for help ignored. Images are often too big, too small, rotated, upside down, out of focus, dimly lit, or of otherwise poor quality, and your handwriting probably isn't as easy to read as you think it is. Images are a hindrance to the helpers as portions of the problem statement or your work can't easily be quoted. Using images also doesn't qualify as filling out the homework template, so your post may be deleted.

 

[Mark44]

please refer to the lower part , it states that |AB|= |AB| cos(\theta)... after eliminate |vector b1 x vector b2|

At the bottom of the third image you have |AC| = |AB|cos($\theta$)