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

Prove that the sum of the squares of the diagonals of a rhombus is equal to the sum of the squares of the 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 diagonals of a rectangle are equal.

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 three xx the sum of the squares of the sides of a triangle is equal to fourxx the sum of the squares of the medians of the triangle.

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

If the diagonals of a rhombus are 8 and 6, then the square of its side is