The diagonals of the two faces of the rectangular parallelepiped are 10 cm and 17 cm
March 27, 2021 | education
| The diagonals of the two faces of the rectangular parallelepiped are 10 cm and 17 cm, and the total lateral edge of these faces is 8 cm, find the volume of the parallelepiped.
All faces of a rectangular parallelepiped are rectangles. The diagonals of the faces form right-angled triangles with their sides.
Let us introduce the notation: a, b, c – edges, d1, d2 – diagonals of faces, common edge с = 8 cm.
Let’s compose the equations:
a ^ 2 + c ^ 2 = d1 ^ 2;
b ^ 2 + c ^ 2 = d2 ^ 2.
a ^ 2 = d1 ^ 2 – c ^ 2 = 10 ^ 2 – 8 ^ 2 = 100 – 64 = 36 = 62;
a = 6 cm.
b ^ 2 = d2 ^ 2 – c ^ 2 = 17 ^ 2 – 8 ^ 2 = 289 – 64 = 225 = 152.
b = 15 cm.
The volume of a parallelepiped is equal to the product of its three dimensions:
V = a * b * c = 6 * 15 * 8 = 720 cm2.
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