| π | 3π | 1 | ||||
cos | *cos | =− | ||||
| 5 | 5 | 4 |
| π | 2π | 1 | ||||
cos | *cos | = | ||||
| 5 | 5 | 4 |
https://matematykaszkolna.pl/forum/147717.html
| π | 3π | 1 | ||||
cos | *cos | =− | ||||
| 5 | 5 | 4 |
| 1 | ||
cos36*cos108=− | ||
| 4 |
| 2sin36*cos36*cos108 | ||
L= | = | |
| 2sin36 |
| sin72*cos(90+18 | sin72*(−sin18) | |||
= | = | = | ||
| 2sin36 | 2sin36 |
| −sin72*cos72 | ||
= | = | |
| 2sin36 |
| −sin144 | 1 | |||
= | =− | =P | ||
| 4sin36 | 4 |
