Just in case you didn't figure it out, He just used algebra to solve for A^2 in the equation: (1/2h)^2 + A^2 = h^2 That solved to: A^2 = (3/4)(h^2) Then he simplified by square rooting A^2 which ends up being A, but you have to do it to both sides so he square rooted (3/4)h^2 which ends up being (3^1/2 / 2)h. Hope that helps...
thanks for the feedback. The problems dealing with 45-45-90 triangles are a review (this is the third video of a series of 5 in the Geometry playlist). Let me know if you think the portion on 30-60-90 triangles is too fast.
I’m going to be honest here. Your explanation was worthless. Your voice is the most annoying thing I’ve ever heard and I had to play this on 2x speed so I didn’t throw up or bore myself to death. Your explanations teach nothing because you spend half the video repeating yourself. If people don’t understand the video the first time they can rewatch it especially when the watch time would be cut in half. Learn how to teach, or don’t do it at all.
@perezallonzo You can imagine that there is a 1 in front of the variables, so it would look like 1A^2 = 1h^2 - 1h^2/4. 1h^2 - h^2/4 have something in common: h^2. If we factor that out, or remove it from the two terms, we get h^2(1 - 1/4) or h^2(4/4 - 1/4) because 4/4 = 1 and we need to have common denominators in order to subtract. So 4/4 - 1/4 = 3/4, and we are left with h^2(3/4), or 3/4h^2 Take the square root of both sides, and we have A = sqrt3/2h
I have a question. My textbook derived the side to be simply the sqr rt of 3, not sqr rt of 3 over 2. Is it because they used the fact that the sides of an equilateral triangle equal to 2 whereas you used the variable h and kept in the process. So sqr rt of 3 over 2 x h=2 gives you simply sqr rt of 3? I think that's right. Make sense? BTW why do the sides of an equilateral triangle equal to 2? Do you have a lesson that discusses this?
chicago618 this was 8 years ago, but I'm facing the same problem now. I was doing practice problems on the Khan Academy website, but felt confused so I tried to Google more info on 30 60 90 triangles. However, everyone else shows sides that measure 2 : 1 : sq rt of 3. I realize here that he divided them all by 2, but I don't get why....
Yeah, he kinda didn't explain what he did there. What he did there was factored out the H^2 from the equation and that left the 1/4. H^2 factored out from H^2 leaves a 1 Do you see that? I would have just done the math as the equation stood as H^2-H^2 /4 . It all comes out the same in the end. Hope it helps.
yea he did it pretty quick at the end. feels like he built it all up with foundations at the start then he randomly got busy at the end and did it in his head. still learned alot though
Why is it that h^2 - (h^2)/4 equal 3/4h^2? Is it because the one forth is subtracting from the h somehow? Sorry if this is a stupid question, my math isn't that good
MrEliteFeet, don't make them equal, you simplify both sides. In this case he took out the power of two by square rooting both sides. If you really want to lear more, watch a video about factoring at Math Bff
I love these videos, but they're always sooooooo laggy. My computer is fairly fast, and I never have any sort of problems with having many things on screen. If I try to scroll, pause, or click a point in the progress bar, there's always a high chance of Firefox (Or internet Explorer) crashes.
Yup I really don't understand where that (1 - ¼) came from... I understand that A² = h² - ¼ of h² is correct. But why are we subtracting 1 from ¼ of h? What is the logic that I am obviously missing here? :C Is it because we are now working with mixed numbers instead of fractions? Cause to me this makes no sense still. :/
holy crap im in 7th grade and their teaching this to me i dont believe it i dont understand one little bit i dont know how the heck you could ever memorize this its impossible maybe my teacher suks :((((((((((
This is really bugging me. Where does my textbook get that each side of an equilateral triangle is 2? I know Mr Khan that you are deriving it using the variable "h". My text says when you make the equilateral triangle "each side is of length 2". It then uses pythg theorem 1^2 + b^2=2^2. It then derives it to sqr rt of 3. Is the text doing something different? This is bugging me to death. Khaaaaan! Khaaaaaan! Khaaaaan! (sorry Im doing my Captain Kirk impersonation, lol) I have no idea, :(
I know this is a year ago but ill reply anyway. Imagine that you don't have the values of 2 variables but only one. Using the theorems here you can in these special triangles get the value of the two others. With pythag you need atleast two variables to solve out the problem. Hope that helps.
With respect to quality and clarity, this presentation would benefit from a make-over.
oml, I had the volume up and the cough scared me so badd😂😂😂
SAMEEE
IT NEARLY KILLED ME!!!
I’ve never been so confused in my life
Lol @ the people who's complaining about quality. This was made in 2007. calm da fak down.
I still don't get it.
same
Assuming you took geometry as a freshman chances are you are in college so me explaining it won't be of much help
Joel Perez i feel dumb i’m taking geometry as a sophomore
@@cupid8041 Same
That cough scared the living shit out of me.
SAMMMMMMMMMMMMMMMMMMMMMEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
ooh, you're a star1? i see hyorin in your pic...
Bruh who watching this in 2020?
El.Indio 54 online school bc of corona bro 😭
@@caileyq4166 Its funny because he started the vid with a cough, and we're all here cause the virus shut down our schools lmao
Swaggasaurus omg 😭😭
2021
@@17Jahseh17 now March 2022. :)
Just in case you didn't figure it out,
He just used algebra to solve for A^2 in the equation: (1/2h)^2 + A^2 = h^2
That solved to: A^2 = (3/4)(h^2)
Then he simplified by square rooting A^2 which ends up being A, but you have to do it to both sides so he square rooted (3/4)h^2 which ends up being (3^1/2 / 2)h. Hope that helps...
thank you
My first time using this... it's been three minutes, and I already understand it. Mostly. Thank you.
.
thanks for the feedback. The problems dealing with 45-45-90 triangles are a review (this is the third video of a series of 5 in the Geometry playlist). Let me know if you think the portion on 30-60-90 triangles is too fast.
U scared me at the beginning XD. Ur voice is soothing
I’m going to be honest here. Your explanation was worthless. Your voice is the most annoying thing I’ve ever heard and I had to play this on 2x speed so I didn’t throw up or bore myself to death. Your explanations teach nothing because you spend half the video repeating yourself. If people don’t understand the video the first time they can rewatch it especially when the watch time would be cut in half. Learn how to teach, or don’t do it at all.
@@symone9114 bro
This dude is the only reason I’m passing geometry
That triangle at 2:36.
am crying
thx, vid helped me a lot. I got a 97 on my math test.
wow ur ancient :V
Lenght of the side x of a 45* triangle with hypotenuse H is: x = H / sqrt(2).
Because 2x / sqrt(2) = x * sqrt(2).
@perezallonzo just distribute the h^2 to the 1-1/4 and you get what he originally had (h^2-h^2/4). He factored out the h^2.
Don't know how I would have passed math w/out Khan Academy!
@perezallonzo You can imagine that there is a 1 in front of the variables, so it would look like 1A^2 = 1h^2 - 1h^2/4.
1h^2 - h^2/4 have something in common: h^2. If we factor that out, or remove it from the two terms, we get h^2(1 - 1/4) or h^2(4/4 - 1/4) because 4/4 = 1 and we need to have common denominators in order to subtract.
So 4/4 - 1/4 = 3/4, and we are left with h^2(3/4), or 3/4h^2
Take the square root of both sides, and we have A = sqrt3/2h
i still dont get how u got 1/4 from h^2
Now I get why the hypotenuse is double the length of the smaller side on a 30 60 90 triangle
Thanks Mr.Kim
I have a question. My textbook derived the side to be simply the sqr rt of 3, not sqr rt of 3 over 2. Is it because they used the fact that the sides of an equilateral triangle equal to 2 whereas you used the variable h and kept in the process. So sqr rt of 3 over 2 x h=2 gives you simply sqr rt of 3? I think that's right. Make sense? BTW why do the sides of an equilateral triangle equal to 2? Do you have a lesson that discusses this?
chicago618 this was 8 years ago, but I'm facing the same problem now. I was doing practice problems on the Khan Academy website, but felt confused so I tried to Google more info on 30 60 90 triangles. However, everyone else shows sides that measure 2 : 1 : sq rt of 3. I realize here that he divided them all by 2, but I don't get why....
the quality though
2007 ... bruh
Cant you use the pothagorean theorem for the first problem since its 90 degrees?
your a life saver
Yeah, he kinda didn't explain what he did there. What he did there was factored out the H^2 from the equation and that left the 1/4. H^2 factored out from H^2 leaves a 1 Do you see that? I would have just done the math as the equation stood as
H^2-H^2 /4 . It all comes out the same in the end. Hope it helps.
yea he did it pretty quick at the end. feels like he built it all up with foundations at the start then he randomly got busy at the end and did it in his head. still learned alot though
Thanks dawg
God bless you.
how did you get from: h^2-(h^2/4) to h^2(1-1/4) ??????????
what
maths
Why is it that h^2 - (h^2)/4 equal 3/4h^2? Is it because the one forth is subtracting from the h somehow? Sorry if this is a stupid question, my math isn't that good
Nice video
was this filmed on a calculator?
Haha ... In the next Module. Funny word. Great vids.
MrEliteFeet, don't make them equal, you simplify both sides. In this case he took out the power of two by square rooting both sides. If you really want to lear more, watch a video about factoring at Math Bff
That cough came outta nowhere- 💀
I love these videos, but they're always sooooooo laggy. My computer is fairly fast, and I never have any sort of problems with having many things on screen. If I try to scroll, pause, or click a point in the progress bar, there's always a high chance of Firefox (Or internet Explorer) crashes.
Watching during CoVid19 Social distancing 😷😋
Yup I really don't understand where that (1 - ¼) came from...
I understand that A² = h² - ¼ of h² is correct. But why are we subtracting 1 from ¼ of h? What is the logic that I am obviously missing here? :C Is it because we are now working with mixed numbers instead of fractions?
Cause to me this makes no sense still. :/
wheres the short and long leg?
Maybe keep it as c squared next time instead of changing it cuz u feel like it?
please please please get or make a pop filter
+Dylan Smith This was almost 10 years ago........
no, cuz you can have a triangle with angles of 90, 46, and 44. :) so on and so forth.
could someone link me the explanation of the simplification at 1:41 ?
ugh i hate math.
Kind of confusing, but waaaay better than my stupid geometry "teacher." B]
how did h squared - h squared/4= h squared times 1- 1/4
why not just use sin,cos,tg ?
I take back everything I said in your video on the gold standard.
KHAN!!!!!!!!!
D-did you just make a Star Trek joke?
holy crap im in 7th grade and their teaching this to me i dont believe it i dont understand one little bit i dont know how the heck you could ever memorize this its impossible maybe my teacher suks :((((((((((
how do you get 4? ugh we are learning this is geometry im confused
(1/2H)squared=(1/2H)*(1/2H)=1/4Hsquared. Because 1/2times1/2 equals 1/4 and H times H equals H squared
@5:25 looks like an Indian tent
who watchin in 2021 tho?
2022
how come a^2=3/4h^2 = a=sqrt3/2*h? I almost have it but someone needs to explain like I'm 5
This is really bugging me. Where does my textbook get that each side of an equilateral triangle is 2? I know Mr Khan that you are deriving it using the variable "h". My text says when you make the equilateral triangle "each side is of length 2". It then uses pythg theorem 1^2 + b^2=2^2. It then derives it to sqr rt of 3. Is the text doing something different? This is bugging me to death. Khaaaaan! Khaaaaaan! Khaaaaan! (sorry Im doing my Captain Kirk impersonation, lol) I have no idea, :(
@775shahrukh 10 months ago i get it now :D
that cough plus earphones equals P A I N
oh and cant we just do a^2+b^2=c^2 instead of all this?
I know this is a year ago but ill reply anyway. Imagine that you don't have the values of 2 variables but only one. Using the theorems here you can in these special triangles get the value of the two others. With pythag you need atleast two variables to solve out the problem. Hope that helps.
cooliceage oh nice I had the same question so thanks for clearing that up
lol thanks but i took the regents already lol
THE COUGH SCARED ME >:D
So why are you smiling... :)
you scared me in the starting
That cough intro though 😆
I was wondering why the sine of 30 is 1/2. Watching this video made me feel incredibly stupid. :(
ur not :D
Khan I'm sorry but you sound exactly like reggie miller
IndyKnox 98 what really?
Why did he explain it in rocket science form?
Suhail saifi roll no 24 nice video
How is 30 degrees half of 90? That doesn’t even make sense
@MultiCarlin23 ook
Afzal Alam roll no 23 nice video
I. don't. understand.
me 2
I was 2 when this was made 😂
Me too 😂
still confused
@perezallonzo yeah i dont get that either :L
*cough* sorry for starting the video with a cough.
Lol
illumintati
lol
jk
@MultiCarlin23 lol
you take to long to get to the point of how to solve it!!
bro what
He lost me at around 7 minutes and 20 seconds
2 dislikes are retar
I don't like math
bla bla math shi ... COUGH.. math stuff lol
oh! would u shut it