MA-664

Finding an unknown in a formula

Lower Sec Maths · Secondary 2 · Hard · Finding an unknown in a formula

A regular tetrahedron has all edges of length 10 cm. Each face is an equilateral triangle.

Using the formula for the area of an equilateral triangle,

A = \dfrac{\sqrt{3}}{4}a^2

, find the total surface area of the tetrahedron, in

\text{cm}^2

, correct to 1 decimal place.

173.2 $\text{cm}^2$
100.0 $\text{cm}^2$
346.4 $\text{cm}^2$
75.0 $\text{cm}^2$

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