Area of an equilateral triangle | Perimeter, area, and volume | Geometry | Khan Academy

Finding the formula for the area of an equilateral triangle with side s

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[MooMooMath]

We use your videos all the time at my school and they are always helpful. I liked your videos so much I started making my own videos to help my class. Thanks for your hard work.
MooMooMath

[ThomasGiles]

The 30 60 90 proof should be before this video in the playlist, I think. I had to go hunting to figure out what you were talking about.

[TiberiusStorm]

Why do you take the square root of 3??

[AlRoderick]

So all equilateral triangles with rational side lengths have irrational areas. I guess that means that any figures constructed of equilateral triangles would be the same (Stars of David, regular hexagons, etc.)

[ghostlyyin]

What a life saver bro 👍 Imma Ace my test

[brianfreeman]

so take the square root of three, times that by half of what "s" originally was, and that's ur height. Multiply what "s" originally was with the height you just found,  and there's ur final answer. I think that's it. You took way longer than necessary to explain that. And you chose a more difficult route and harder to understand. But ty I think I get it now:)

[jpautabarber]

No need to calculate for the height or try to figure out the height to find the area of this equilateral triangle . Just use this formula s/2 × ✓3.

[yNeza]

I don't get the square root of 3 over 2 bit, couldn't you just used Pythagoras to find out the height?

[jpautabarber]

Khan Academy I love your videos but could you make a video on finding the area of an equilateral triangle shorter, because there's a shorter way easier way to find the area of an equilateral triangle. I found this aying around with the values. You can prove it. The formula is ( it only works for equilateral triangles) Area = s/2 × ✓3.

Area of that equilateral triangle is s over two times square root of 3. Thank me later.

[jpautabarber]

I apologize I made a mistake, S divided by two, square the quotient and multiply by ✓3 . I don't know how to turn that into a formula but that's accurate.

[yyl]

Could any of you guys tell me if u know which part of video contains the explanation about the 30:60:90 ?
Thank you

[rubyyxlc]

speed .75x on settings helps a lot lol around the hard parts he talks 100 words per minute.

[StripesofShay]

i understand radical 3 times s, but why do you divide that by 2?

[mikebruce]

this vid is fucking amazing thank you now # 53 on my homework is going to get dominated

[sanfran]

why the height is Xsqrt3 ? how come i know the rule for 30 60 90 triangle but I would like to know why sqrt3

[kcguitar]

Can’t you just use 1/2 x Base x Height to find the area?