As shown in the figure, in the triangle ABC, the angle ABC = 30 degrees, take BC and AC as sides, make equilateral △ BCD and equilateral △ ace, and connect be. To prove, AB square + BC square = be square

Connecting ad, because △ BCD and △ ace are equilateral triangles, so: BD = BC = DC, AC = EE, angle DCB = angle ace = 60 °, so: angle DCB + angle BCA = angle ECA + angle BCA, that is: angle DCA = angle BCE, so: Triangle DCA is equal to triangle BCE, so: be = ad

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