In a parallelogram, the sides and one of the diagonals are 4cm, 6cm, 7cm

In a parallelogram, the sides and one of the diagonals are 4cm, 6cm, 7cm, respectively. Find the length of the other diagonal of the parallelogram.

Let us use the parallelogram property, according to which the doubled sum of the squares of the sides of the parallelogram is equal to the sum of the squares of its diagonals.

AC ^ 2 + BD ^ 2 = 2 * (AD ^ 2 + CD ^ 2).

BD ^ 2 = 2 * (AD ^ 2 + CD ^ 2) – AC ^ 2 = 2 * (36 + 16) – 49 = 104 – 49 = 55.

ВD = √55 cm.

Answer: The length of the other diagonal is √55 cm.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.