Definition: A kite is a quadrilateral with two pairs of adjacent sides that are equal in length.

Example: For an equilateral triangle, the area can be calculated using the formula P=a²√3/4, where 'a' is the length of a side.

Highlight: The page emphasizes that the measure of an inscribed angle in a circle is half the measure of the central angle subtended by the same arc.

Vocabulary: An inscribed circle is a circle that is tangent to all sides of a polygon from within.

Definition: Thales' theorem states that if a line is drawn parallel to one side of a triangle intersecting the other two sides, it divides those sides in the same ratio.

Example: The Side-Angle-Side (SAS) congruence criterion states that two triangles are congruent if two sides and the included angle of one triangle are equal to the corresponding parts of the other triangle.

Highlight: The Angle-Angle-Angle (AAA) similarity criterion states that two triangles are similar if all three corresponding angles are equal.

Example: For the Side-Side-Side (SSS) similarity criterion, two triangles are similar if the ratios of the lengths of their corresponding sides are equal.

Vocabulary: Planimetria refers to the study of plane geometry, focusing on two-dimensional shapes and their properties.

Highlight: The page emphasizes the importance of understanding basic formulas for each shape, such as P=a² for the area of a square and P=ab for the area of a rectangle.