filmov
tv
A line makes angles \( \alpha, \beta, \gamma, \delta \) with the fo...
Показать описание
A line makes angles \( \alpha, \beta, \gamma, \delta \) with the four diagonals of a cube, then prove that
\[
\cos ^{2} \alpha+\cos ^{2} \beta+\cos ^{2} \gamma+\cos ^{2} \delta=\frac{4}{3}
\]
\[
\cos ^{2} \alpha+\cos ^{2} \beta+\cos ^{2} \gamma+\cos ^{2} \delta=\frac{4}{3}
\]
0:11:01
0:15:41
0:06:25
0:00:26
0:02:21
0:19:45
0:01:29
0:01:31
0:02:49
0:01:26
0:06:04
0:07:12
0:25:36
0:07:15
0:01:59
0:01:36
0:15:27
0:01:06
0:01:42
0:02:08
0:02:40
0:02:06
0:02:05
0:06:49