Prove that the sum of the squares of the diagonals of parallelogram is equal to the sum of the squares of its sides.

prove by vector method that the sum of the squares of the diagonals of a parallelogram is equal to the sum of the squares of its sides.

Prove by vector method that the sum of the square of the diagonals of a parallelogram is equal to the sum of the squares of its sides.

Prove that the sum of the squares of the sides of a rhombus is equal to the sum of the squares of its diagonals.

Prove that the sum of the squares of the sides of a rhombus is equal to the sum of the squares of its diagonals.

Prove analytically that the sum of square of the diagonals of a rectangle is equal to the sum of squares of its sides.

Prove that three times the sum of the squares of the sides of a triangle is equal to four times the sum of the squares of the medians of the triangle.

Prove that in a parallelogram, the sum of the squres of the diagonals is equal otthe four times the sum of the square of three conterminos edges.

Prove that the sum of two consecutive angles of a parallelogram is 180^(@).

Prove that in any parallelogram the sum of squares of the diagonals is twice the sum of the squares of two adjascent sides. Also show that the difference of the squares on two adjacent sides is equal to the rectangle contained by either diagonal and the projection of the other upon it.

The square of the diagonal of a square is 50 sq. units. Find the side of the square.