mathinschool.com
numbers and algebraic expressions
logic, sets, intervals
absolute value
function and its properties
linear function
quadratic function
polynomials
rational function
exponential function
logarithm
number sequences
limits of sequences and functions
derivative and integral of functions
trigonometry
plane geometry
analytic geometry
solid geometry
combinatorics
probability
elements of statistics
kropki game

Two triangles are congruent if we can first triangle superimposes to second and get one the same triangle. The congruent triangles have the same size and shape. Congruent polygons. Three methods for showing triangles to be congruent. (sss) side -- side -- side. Equivalent sides of a triangle are equal. (sas) side -- angle -- side. Equivalent two sides of a triangle are equal and angle between them. (asa) angle -- side -- angle. Equivalent two angles and their common side of a triangle are equal.