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ceviri

but wait, why is it the pentagon inequality and not the triangle inequality?

(hey look at me I finished the lecture)

peanut

This is clearly not a pentagon. (hey I finished the last slide as well)

keenan

:-)

rbunny

Thanks for keeping the slides entertaining! :)

Jamie

When I first saw this, I thought that it might be typo and Professor Crane just read it out when filming the video. When I finished this video, I found that it is a designed trick to make us point out the mistakes or ask our question bravely. Thanks a lot for Professor Crane's well-designed lecture and slides!

whc

haha

small_potato__

In the beginning part of this slide, you said that we need to take the magnitude of c, because it would be bad to scale by a negative number. Wouldn't scaling my a negative number just flip the direction of the vector (or rotate by 180 degrees)?

dranzer

Scaling with a negative number will cause the problem that norm will be negative if we omit the absolute. You know the magnitude doesn't make sense to be negative. From a geometrical point of view, also the absolute of c makes sense. Multiplying -1 to v, will keep the magnitude same but just change the direction.