Level:
Project ID:
1103101208
Accepted:
1
Clonable:
0
Easy:
0
Let \( ABCD \) be a regular tetrahedron with an edge length of \( 5\,\mathrm{cm} \). Let \( \varphi \) be the angle between the face \( ABD \) and the base plane \( ABC \) (see the picture). Choose the correct expression for \( \varphi \):
\( \cos\varphi=\frac13 \)
\( \mathrm{tg}\,\varphi=6\sqrt3 \)
\( \mathrm{tg}\,\varphi=3\sqrt2 \)
\( \cos\varphi=\frac23 \)