Spheres Intersecting (1 Viewer)

[HSCya1234567]

Does anyone know how to do part ii, I would be grateful thankyou!

 

[SadCeliac]

I hate these questions

Will give it a go

 

[SadCeliac]

Are there no sols??

 

[HSCya1234567]

there are but they dont make sense its from the plc 2022 trial

hope sdd is slaying and chem slayed i'd love to help but i do latin instead lol

 

[SadCeliac]

This is my solution for part (i)

 

[HSCya1234567]

yeah nice that's how i solved it too but much more nicely worked out than mine ahaa

 

[SadCeliac]

yeah nice that's how i solved it too but much more nicely worked out than mine ahaa

lol np

I have NO IDEA HOW TO DO ii WTAF lmaoo

 

[HSCya1234567]

HAHAHA here are the soluns that makes me feel better though maths x 2 is like the gift that keeps giving

 

[SadCeliac]

HAHAHA here are the soluns that makes me feel better though maths x 2 is like the gift that keeps giving


View attachment 39199

that makes no sense though - where does the 2/3 come from???

Basically (my understanding):
let S1 centre be A
let S2 centre be B
find vector between A and B : AB

let their intersection be point P
since we know that they intersect (they are tangential), and we know their radii, AB and AP must be in the ratio 4/16 <-- BUT IT ISNT??

 

[HSCya1234567]

I KNOW thats where i got confused

 

[SadCeliac]

I KNOW thats where i got confused

I'm gonna do some digging through my various worksheets to find a similar question and see if I can find a nice solution :/

 

[SadCeliac]

EDDIE WU

^^ play from 11:36

 

[SadCeliac]

@HSCya1234567 - here is a clearer solution for part ii

The solutions were right, just skipping all the steps and providing no explanation. If my explanation below doesn't help, then I really recommend that above Eddie Wu video - it actually makes so much sense (you'd hope - he's a teacher)



Basically we imagine P as lying on AB (where A is one center and B is the other)
Then we say, okay, that means that AP is a scalar of AB
So we find AB (which we did in part i)
Then, because we know the radii, we can say that P lies 4/6ths of the way along AB
Therefore AP = 4/6 AB = 2/3 AB

And then you solve from there (I did it by splitting up AP into AO + OP, because that's easier for me to visualise)

HOPE THIS HELPS!!!!! <3

 

[HSCya1234567]

OMG THANKYOU bro ur amazing

 

[SadCeliac]

No worries - I struggled with this as much before watching the video lmao

 

[SadCeliac]

@HSCya1234567 does it all make sense though???

 

[HSCya1234567]

yes it does thankyou!

 

[HSCya1234567]

bro how did you do both maths adv and maths x 1 accelerated i have a new level of respect for you

 

[synthesisFR]

bro how did you do both maths adv and maths x 1 accelerated i have a new level of respect for you

geez get a room you two
(by room i am referring to the conversations u can create on bos that a private)

 

[SadCeliac]

bro how did you do both maths adv and maths x 1 accelerated i have a new level of respect for you

the literal exact same way every other regular mx1 student does advanced and mx1 - just a year early??

we just skipped year 10 math / caught it up at the start of year 11 idrk or remember