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 October 4th, 2017, 10:46 AM #1 Newbie   Joined: Oct 2017 From: Houston Posts: 1 Thanks: 0 Missing Side Calculation I'm trying to find the lengths of A and B in the photo. Any help?
 October 5th, 2017, 07:42 AM #2 Global Moderator   Joined: Dec 2006 Posts: 19,870 Thanks: 1833 As (1086' + A)/A = 13744/13312, A = 1086' × 13312/(13744 - 13312) = 301184'/9.
October 5th, 2017, 08:01 AM   #3
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Quote:
 Originally Posted by klbevan I'm trying to find the lengths of A and B in the photo. Any help?
SkipJack's got it. Basically, you exploit the fact that the angles for the little triangle and the big triangle are the same, so if $\displaystyle \theta$ is the angle at the top-right bit of the triangle, you then have

$\displaystyle \tan \theta = \frac{13312}{A}$

for the small triangle and

$\displaystyle \tan \theta = \frac{13744}{(1086+A)}$

for the large triangle. Equating the two gives

$\displaystyle \frac{13312}{A} = \frac{13744}{(1086+A)}$

which can then be solved for A using basic algebra. Once A is known, you can either use trigonometry or Pythagoras' theorem to get B using the small triangle dimensions.

 Tags calculation, missing, side

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