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length of common tangent?? (1 Viewer)

5647382910

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I know what a common tangent is but what are you actually being asked to find in this:

two circles of radii 5cm and 8cm touch each other externally. Calculate the length of the common tangent

Cant the length of the tangent be anything?
 
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lyounamu

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5647382910 said:
I know what a common tangent is but what are you actually being asked to find in this:

two circles of radii 5cm and 8cm touch each other externally. Calculate the length of the common tangent

Cant the length of the tangent be anything?
That's interesting. I don't know either. The wording of the question is confusing.
 

5647382910

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man wtf, this is fitzpatrick, the next 4 q's ask for the length of the common tangent, this is bullshit
 

Timothy.Siu

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5647382910 said:
man wtf, this is fitzpatrick, the next 4 q's ask for the length of the common tangent, this is bullshit
there is,
u can find it...i'll do it soon,
edit: this is if i think i know what i'm trying to find.
 
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Timothy.Siu

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5647382910 said:
ye, but what did u calculate?
yeah i got that too,
u just draw a diagram, and using tangent to centre is right angle, u can make a triangle with 13 as the hypotenus (8+5) and a side of 3, so the other side is square root 160
edit: i'll draw it in paint
 

gurmies

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Agreed. I'm so bad at drawing using paint, thus I can't post my solution:( But yeah, draw a line from the centre of the SMALLER cirlce, meeting the larger radius to the tangent at a right angle. Therefore, the smaller part will be 3 cm, and the larger will be 5 cm. Now use pythagoras' theorem and say 13^2 - 3^2 = 4root10. That's also the length of the common tangent..
 

lyounamu

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Timothy.Siu said:
and u can like sorta shift the 13cm side down, and make the triangle
Never seen that kind of question before. But I guess it's part of the learning curve. Thanks for posting that up,
 

5647382910

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lol, i was finding the tangent through the point of contact
thanks for the help guys
 

lyounamu

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5647382910 said:
lol, i was finding the tangent through the point of contact
thanks for the help guys
The common tangent is not only restrctied to the tangent through the point of contact. :eek:
 

madsam

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lyounamu:
My HSC subjects =
(maths + business +bio + english + cosmo) + i(sor)
Thats hilarious.... but it really shouldnt be =\
do you do 4unit?
 

lyounamu

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madsam said:
lyounamu:


Thats hilarious.... but it really shouldnt be =\
do you do 4unit?
Why shouldn't it be?

4 subjects are real but one is just an imaginary subject.

Yeah, I do 4 Unit Mathematics.
 

DrFunk

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whilst I am amused by your sig, it isn't perfect as i is the imaginary part, and in the form x +iy y stands in place of a real number. So yeah... You're trying to say religion is imaginary but kinda failed...
 

lyounamu

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DrFunk said:
whilst I am amused by your sig, it isn't perfect as i is the imaginary part, and in the form x +iy y stands in place of a real number. So yeah... You're trying to say religion is imaginary but kinda failed...
Hey, the order doesn't really matter (in this sig). I am aware that i goes next to the number but I cannot be bothered to change it.
 

youngminii

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lyounamu said:
Hey, the order doesn't really matter (in this sig). I am aware that i goes next to the number but I cannot be bothered to change it.
I think what he thinks is that you tried to make SoR 'imaginary'. As in, SoR = i

Anyways DrFunk, it is a joke, and it is supremely.. stupid to talk about it so literally
 

lyounamu

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youngminii said:
I think what he thinks is that you tried to make SoR 'imaginary'. As in, SoR = i

Anyways DrFunk, it is a joke, and it is supremely.. stupid to talk about it so literally
Nah, actually I was trying to make it as an imaginary part.

I really am not good at copying from someone else's idea.
 

addikaye03

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lyounamu said:
Nah, actually I was trying to make it as an imaginary part.

I really am not good at copying from someone else's idea.
Did you copy from that VDS guy? and what 4U textbook do you use dude?
and how do you think u went at 3u this year?
 

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