15. The length of each edge of a regular tetrahedron,
whose faces are identical equilateral triangles, is
8 cm. Find its
(i) slant height
(ii) volume.
Hint: All sides are equal. The centre of an equilateral
triangle is of its height h.

Respuesta :

Slant height of tetrahedron is=6.53cm

Volume of the tetrahedron is=60.35[tex]\mathrm{cm}^{3}[/tex]

Given:

Length of each edge a=8cm

To find:

Slant height and volume of the tetrahedron

Step by Step Explanation:

Solution;

Formula for calculating slant height is given as

Slant height=[tex]\sqrt{\frac{2}{3}} a[/tex]

Where a= length of each edge

Slant height=[tex]\sqrt{\frac{2}{3}} \times 8[/tex]

                     =[tex]\sqrt{0.6667} \times 8[/tex]

                     =[tex]0.8165 \times 8[/tex]=6.53cm

Similarly formula used for calculating volume is given as

Volume of the tetrahedron=[tex]\frac{a^{3}}{6 \sqrt{2}}[/tex]

Substitute the value of a in above equation we get

Volume=[tex]\frac{8^{5}}{6 \sqrt{2}}[/tex]

            =[tex]\frac{512}{6 \sqrt{2}}[/tex]

            =[tex]\frac{512}{6 \times 1.414}[/tex]

Volume=[tex]512 / 8.484[/tex]=60.35[tex]\mathrm{cm}^{3}[/tex]

Result:

Thus the slant height and volume of tetrahedron are 6.53cm and 60.35[tex]\mathrm{cm}^{3}[/tex]