Question

The Pyraminx is a Rubik’s cube-toy in the shape of a tetrahedron. The Pyraminx shown below has edges of 15cm long and a vertical height h=12.2 cm. The Triangle drawn with dashed lines is a right triangle. What is distance r?

Answer 1

The distance r is
`8.7\ cm`

Explanation:

we know that

Applying the Pythagoras Theorem

`c^(2)=a^(2)+b^(2)`

where

c is the hypotenuse

a,b are the legs

In this problem we have

`c=15\ cm`

`a=r`

`b=h=12.2\ cm`

substitute and solve for r

`15^(2)=r^(2)+12.2^(2)`

`225=r^(2)+148.84`

`r^(2)=225-148.84`

`r^(2)=76.16`

`r=8.7\ cm`