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 March 4th, 2013, 12:34 PM #11 Newbie   Joined: Mar 2013 Posts: 8 Thanks: 0 Re: Find all the sides of this triangle. For me. First: QB = PB CQ = RC follows that beta = angleQBP = 2*arctg(r/QB) gamma = angleQCR = 2*arctg(r/CQ) AC = CB * sin (beta) / sin(180°- beta - gamma) = 13 AB = CB * sin (gamma) / sin(180°- beta - gamma) = 15
March 4th, 2013, 01:24 PM   #12
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Re:

Quote:
Originally Posted by skipjack
Quote:
 Originally Posted by McPogor Eventually x=12.
Incorrect. You omitted the working at precisely the point where you slipped up.
There's subtraction error: 104-90=24
Correct x=7; AC=13; AB=15

 March 4th, 2013, 04:03 PM #13 Senior Member   Joined: Dec 2012 Posts: 450 Thanks: 0 Re: Find all the sides of this triangle. Bad news for everyone. I forgot to include the rule:don't use trignometry.
 March 4th, 2013, 05:12 PM #14 Global Moderator   Joined: Dec 2006 Posts: 20,833 Thanks: 2161 Trigonometry isn't needed to prove Heron's formula, and hence the formula I linked to originally.
 March 4th, 2013, 05:15 PM #15 Senior Member   Joined: Dec 2012 Posts: 450 Thanks: 0 Re: Find all the sides of this triangle. I was referring to Mcpogor.
 March 4th, 2013, 05:28 PM #16 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,597 Thanks: 1038 Re: Find all the sides of this triangle. No trig: Let b = AC; then AB = b+2 Using Heron's formula: s=(14 + b + b+2)/2 = b+8 ; leads to AreaABC = SQRT[48(b^2 + 2b - 4] Carry on this way: SQRT[48(b^2 + 2b - 4] = Area(triangles AOC + BOC + AOB)
 March 4th, 2013, 05:30 PM #17 Senior Member   Joined: Dec 2012 Posts: 450 Thanks: 0 Re: Find all the sides of this triangle. You got it,Denis...
March 4th, 2013, 05:37 PM   #18
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Re: Find all the sides of this triangle.

Quote:
 Originally Posted by mathmaniac You got it,Denis...
Oh...you already knew...are you Albert's long-lost-son ? :P

 March 4th, 2013, 05:40 PM #19 Senior Member   Joined: Dec 2012 Posts: 450 Thanks: 0 Re: Find all the sides of this triangle. I am an Albert fan. And more than that these are the only sort of problems I think I can do good..... More to come from the Albert fan....

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