Question 649460
* http://static.tumblr.com/o5ekeuz/2OOma6taj/abc.png
This has 2 sketches, says to find ABC.
The 1st one has no B in it.
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For the 2nd one, all you can say is ABC = arctan((x^2 + 81)/12x)
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If the 12x and the x^2 + 81 are the angles, and not the sides, then
x^2 + 12x + 81 = 90
x^2 + 12x - 9 = 0
*[invoke solve_quadratic_equation 1,12,-9]
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Ignore the negative numbers
12x =~ 8.4984 degs
x^2 + 81 =~ 81.5016 degs

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and * http://static.tumblr.com/o5ekeuz/hBhma6td6/abcc.png
In that one, if the 3x and the 10x/3 are the angles, then
3x + 10x/3 = 90 degs
9x + 10x = 270
x = 270/19 degs
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3x = 810/19 degs =~ 42.63 degs
10x/3 =~ 47.37 degs