Cubic difference formula: a 3-b 3 = (a-b) (a 2+ab+b 2)

Cross multiplication

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Vieta theorem

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A triangle * * * has six hearts:

Heart: The intersection of bisectors of three angles is also the center of the inscribed circle of a triangle.

Attribute: The distances to three sides are equal.

Eccentricity: the intersection of three perpendicular lines is also the center of the circumscribed circle of the triangle.

Attribute: The distances to the three vertices are equal.

Center of gravity: the intersection of three midlines.

Property: The distance from the bisector of the three median lines to the vertex is twice the distance from the midpoint of the opposite side.

Vertical center: the intersection of straight lines of three heights.

Attribute: This point is divided into two parts of each high line.

the intersection string theorem

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Truncated chord theorem

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Property Theorem of Two Connected Circles

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Alternative method

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Properties of quadrilateral inscribed in a circle

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