As shown in the figure, in the triangle ABC, C = 2 b. prove: the square of ab - the square of AC = AC times BC The graph is an obtuse triangle

As shown in the figure, in the triangle ABC, C = 2 b. prove: the square of ab - the square of AC = AC times BC The graph is an obtuse triangle

Make the bisector of angle c, intersect AB with D, ∠ ACD = ∠ DCB = ∠ B, then DC = dB, and ∠ A is the common angle, so the triangle ADC is similar to the triangle ACB, and it is concluded that three groups of corresponding line segments are proportional, then AC square = ab times ad, AC times BC = AB times CD, the two formulas are added, the right side is ab times AD + AB times CD = AB (AD + CD) = AB, the left AC square moves to the right side, and it becomes the square of AC times BC = ab - the square of AC, that is the square of AB times BC