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Similar Triangles

Hi there, I need some help with the last 3 questions. Also, please check whether my answers for the questions are correct or not. Thanks! :smile:
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Reply 1
Avatar for Notnek
Notnek
21
Original post by strangepath
Hi there, I need some help with the last 3 questions. Also, please check whether my answers for the questions are correct or not. Thanks! :smile:

5) First find AC by comparing triangles ADE and ABC. Then this will give you the length of EG.

Once you have EG, you can compare triangles ADE and AFG. The scale factor can be found by comparing the lengths AE=4 and AG=4+EG


6a) Can you prove similarity? There are two pairs of alternate angles and one pair of opposite angles. That's enough to show that the three angles are common to both triangles.


6b) AB : DC = 3 : 7 so since the triangles are similar, this ratio holds for all pairs of corresponding lines: BE : EC = 3 : 7, AE : ED = 3 : 7. Can you use BE : EC = 3 : 7 to find BE : BC?


7a) Notice that the side AP has been folded to make the line PA' so AP = PA' = x

Can you use Pythagoras in triangle PBA' to find x?

Then have a go at the next parts and post all your working/ideas if you're stuck.
(edited 11 years ago)
Reply 2
Avatar for dudefrom93
dudefrom93
OP
11
Is this alright?
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Reply 3
Avatar for dudefrom93
dudefrom93
OP
11
and also if you have time please check my answers for other questions. thanks alot :biggrin:
Reply 4
Avatar for Notnek
Notnek
21
Original post by strangepath
Is this alright?

Your answers are all correct but you need to go into more detail for the proof in 6a. Just saying <A=<D isn't a proof until you explain why.

I'll check your other answers a bit later. Are you OK with 7?
Reply 5
Avatar for dudefrom93
dudefrom93
OP
11
Original post by notnek
Your answers are all correct but you need to go into more detail for the proof in 6a. Just saying <A=<D isn't a proof until you explain why.

I'll check your other answers a bit later. Are you OK with 7?

Thanks! I got the solution from other forum. Yeah Q7 is quite similar to the one in my notes so I think I am fine with it. Once again, thanks alot :biggrin:
Reply 6
Avatar for Notnek
Notnek
21
Original post by strangepath
and also if you have time please check my answers for other questions. thanks alot :biggrin:

1a) You made a typo, saying <RQR instead of <PQR. Otherwise OK.

b) Correct

c) Correct

I don't have time to check the others today. Sorry :smile:
(edited 11 years ago)
Reply 7
Avatar for dudefrom93
dudefrom93
OP
11
Original post by notnek
1a) You made a typo, saying <RQR instead of <PQR. Otherwise OK.

b) Correct

c) Correct

I don't have time to check the others today. Sorry :smile:

Oh didn't see that :tongue: thanks for all the help :biggrin:

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