Answer:
x = 16
Step-by-step explanation:
The equation shown can be solved this way.
x^2 +(x -4)^2 = 20^2
x^2 +x^2 -8x +16 = 400
2x^2 -8x -384 = 0
x^2 -4x -192 = 0
(x -16)(x +12) = 0
The positive solution is ...
x = 16
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Since this makes use of the Pythagorean theorem, you've probably run across the 3-4-5 triangle. You often find scaled versions of it in algebra and geometry problems. Here, it is scaled by a factor of 4 to give a 12-16-20 triangle as half of the display screen.
The 3-4-5 triple is the only Pythagorean triple that is an arithmetic sequence. So, if the difference in side lengths is 4 and the diagonal is 5×4, you can be pretty certain that x = 4×4 and x-4 = 4×3.
