The parallelogram is divided into 12 triangles with equal area by diagonal lines, and four groups. In congruent triangles, the bit line is parallel to half of the third side of the triangle. There is a parallelogram with right angles, a quadrilateral diamond with equal diagonals and three right angles, and a group of parallelograms with equal adjacent sides and four equal sides. Diagonal lines are equal, and each diagonal line bisects a set of diagonal lines. The area of a diamond is half of the diagonal product. Four sides of a square are equal, four corners are right angles, a group of rectangles with equal adjacent sides, a group of parallelograms with equal adjacent sides and a right angle, and an isosceles trapezoid with equal diagonal and trapezoid (two waists are equal and the bottom angles on the same bottom are equal).

Diagonal equality