Introduction to radians | Unit circle definition of trig functions | Trigonometry | Khan Academy

Understanding the definition and motivation for radians and the relationship between radians and degrees

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Trigonometry on Khan Academy: Big, fancy word, right? Don't be fooled. Looking at the prefix, tri-, you could probably assume that trigonometry ("trig" as it's sometimes called) has something to do with triangles. You would be right! Trig is the study of the properties of triangles. Why is it important? It's used in measuring precise distances, particularly in industries like satellite systems and sciences like astronomy. It's not only space, however. Trig is present in architecture and music, too. Now you may wonder...how is knowing the measurement and properties of triangles relevant to music?? THAT is a great question. Maybe you'll learn the answer from us in these tutorials!

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[arjunsogarwal]

RAIDUSESESESESESESESESESESES, wow what a word

[stevedl]

I think radians should be taught from Primary School, rather than degrees. Radians are obviously intrinsic to the circle, whereas degrees are not. Alas, I still find it difficult to think in terms of radians. 

[raithigovender]

aw. I was so excited to comment RAAAADIUSSSES then I saw the comments section and was like...yeah nvm

[pboytrif]

2:46 The moment I decided I liked the video... "I'm gonna attempt to draw a circle *wobbly not <3<3

[The_Pariah]

That was a very good way of explaining this.
I've been out of high school long enough to have forgotten a lot of trig. Now that I'm doing programming, this stuff is needed and these refresher videos really help (especially when they're well done like this one).

[Jam-nhwb]

U saying radiuseseseseseseseses drove me insane, I literally couldn’t pay attention to the video 😂

[sirwaffle]

i never appreciate your circle drawing skills until i have to draw a circle myself

[sunnylefabulous]

i knew from the moment our teacher started explaining this in class there'd be our lord and saviour, Sal Khan, who would explain this much, much better

[timothycarney]

Radiuseseses?!? Radii! Radii! Radieye! RADI👁!

[muninnhugin]

very helpful! cracked me up every time he said radiuseseseses =)

[amrsaleh]

"just to show u this isn't voodo" 😂😂😂😂

[Cesariono]

The definition of the radian suddenly makes so much sense. I used radians in my calculations but I never really understood why they even bothered. Now my mind has been blown.

[yeo]

You haven't lost yet and you have more to achieve

[DopeBoysClan]

I just had a "I UNDERSTAND" moment.  I would have not resorted to these videos, along with the rest of the people here had teachers derived the meaning to mathematical concepts, instead of saying "here it is, use it".  The amount of stupidity evident in today's education is absolutely mind-blowing, unfathomable.  I can only but barley understand the teachers motives for not deriving and explaining where particular principles come from, that of which is they don't care, they want the paychecks and to go home.  Fuck society man.    

[meightyalliu]

this video is clear!
save my life from digging into textbook:P

[callumsimpson]

What program do they use for the drawing?

[sourabhuwusingh]

A great explanation!
Khan Academy is a great place to learn.

[saflanix]

My teacher recorded a few videos during quarantine and I never watched them cuz these are so much better☺️

[bluewolf]

I learned alot today, Radiuseseseses are very important...😂😂😂😂

[namraaah]

if u still don't get it don't worry just read the textbook or whatever and keep trying to understand and then watch the video...i swear you'll get it.I have been spending the whole day trying to understand this and now i finally get it.time taken-approx 6 hours.dude...