The side length of a diamond is 2 cm. Find the square sum of the diagonal length of the diamond

The side length of a diamond is 2 cm. Find the square sum of the diagonal length of the diamond

Let the diagonal length of the diamond be 2a, 2b
Then a ^ 2 + B ^ 2 = 2 ^ 2, both sides multiply by 4
(2a)^2+(2b)^2 = 16
Sum of squares of diagonal length of diamond = 16

If a diamond changes its side length to two, what is the sum of the squares of the two diagonal lengths of the diamond?

16

The area of a diamond is equal to half the product of its diagonal length

The diagonals of the diamond are perpendicular to each other and divided into four equal right triangles. If the diagonals of the diamond are 2a and 2B, the area of one right triangle is AB / 2, and the area of the diamond is AB / 2 * 4 = 2Ab = half of the product of the diagonals
Is that ok?

How to find the sum of squares of constant column?
The sum of the first n terms of the sequence {n (n + 1)} is?

Sum of the first n terms of sequence {n (n + 1)} = (1 + 1 ^ 2) + (2 + 2 ^ 2) + (3 + 3 ^ 2) +. + (n + n ^ 2)
=(1+2+3+...+n)+(1^2+2^2+.+n^2)=n(n+1)/2+(1/6)[n(n+1)(2n+1)]