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numbers and algebraic expressions
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function and its properties
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polynomials
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exponential function
logarithm
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trigonometry
plane geometry
analytic geometry
solid geometry
combinatorics
probability
elements of statistics
kropki game

Right trapezoid. Isosceles trapezoid. The area of a trapezoid. a - bases, h - altitude. A = (a + b) / 2 * h. The angles in a trapezoid: α + δ = 180°. β + γ = 180°.