If the edges of a rectangular parallelepiped are a,b, c, prove that the angles between the four diagonals are given by `cos^(-1)"((pma^(2)pmb^(2)pmc^(2))/(a^(2)+b^(2)+c^(2)))`.

If the edges of a rectangular parallelepiped are a ,b ,c prove that the angles between the four diagonals are given by cos^(-1)((a^2+-b^2+-c^2)/(a^2+b^2+c^2))dot

If the edges of a rectangular parallelopiped are a, b and c, show that the angles between the four diagonals are given by cos^-1frac{a^2+-b^2+-c^2}{a^2+b^2+c^2}

If the edges of a rectangular parallelopiped are 3,2,1 then the angle between a pair of diagonals is given by

If the edges of rectangular parllelopiped are 3,2,1 then the angle between two diagonals out of 4 diagonals id

If the edges of a rectangular parallelopiped are of lengths a, b, c, then the angle between four diagonals are cos^-1((+- a^2 +-b^2 +- c^2)/(a^2+ b^2 + c^2)) .

Show that tha angles between the diagonals of a rectangular parallelopiped having sides a,b and c are cos^(-1)((|alpha|)/(a^(2)+b^(2)+c^(2))) , where alpha=pma^(2)pmb^(2)pmc^(2)and|alpha|!=a^(2)+b^(2)+c^(2) . Hence find the angle between the diagonals of a cube.

Prove that (1+cos(A-B)cosC)/(1+cos(A-C)cosB)=(a^(2)+b^(2))/(a^(2)+c^(2))

Prove that (1+cos(A-B)cosC)/(1+cos(A-C)cosB)=(a^(2)+b^(2))/(a^(2)+c^(2))

Prove the followings : If cos^(-1)a+cos^(-1)b+cos^(-1)c=pi then a^(2)+b^(2)+c^(2)+2abc=1 .

Prove that: (1+ cos (A-B) cos C)/(1+ cos (A-C) cos B) = (a^(2) +b^(2))/(a^(2) + c^(2))