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# Need help with showing some triangles are similar. watch

1. Hi, I was reading a math book and it said triangles PQT and PTR are similar, like it was kind of obvious or something. I tried to prove this for an hour but to no avail. Can someone please enlighten me? Thanks.

I assume that angle QTP will be equivalent to PRT, but I can't see any clear way of that being the case.
Edit: How do I rotate the image? Sorry.
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2. (Original post by CancerousProblem)
Hi, I was reading a math book and it said triangles PQT and PTR are similar, like it was kind of obvious or something. I tried to prove this for an hour but to no avail. Can someone please enlighten me? Thanks.

I assume that angle QTP will be equivalent to PRT, but I can't see any clear way of that being the case.
Edit: How do I rotate the image? Sorry.
Angle PTQ = angle PRT by the Alternate Segment Theorem. Hence the three angles of the triangles are the same.
3. (Original post by Smaug123)
Angle PTQ = angle PRT by the Alternate Segment Theorem. Hence the three angles of the triangles are the same.
**** im so stupid cant believe i've been working on that problem for more than an hour and i overlooked that thank u
4. (Original post by CancerousProblem)
**** im so stupid cant believe i've been working on that problem for more than an hour and i overlooked that thank u
It took me about five minutes. Don't worry.

ETA: sorry, I didn't mean that to read like "I'm twenty times better at maths than you" - I meant "it was sufficiently nonobvious to me that I don't blame you at all for not seeing it".
5. (Original post by Smaug123)
I meant "it was sufficiently nonobvious to me that I don't blame you at all for not seeing it".
I agree. I took me about 5 minutes too. I was completely stumped at first, in fact. The book is very misleading in the way it's presented: "Observe that .." makes it sound like only a simpleton couldn't see it.

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