| 1 | ||
cos120+cos10= 2cos65*cos55 i cos5+ cos15=2cos5*cos10 i cos120= − | ||
| 2 |
| 1 | 1 | |||
L=cos5* | *2cos65*cos55= | cos5*(cos120+cos10)= | ||
| 2 | 2 |
| 1 | 1 | 1 | 1 | |||||
= − | cos5+ | cos5*cos10 = | *2cos5*cos10− | cos5= | ||||
| 4 | 2 | 4 | 4 |
| 1 | 1 | 1 | 1 | |||||
= | (cos5+cos15)− | cos5 = | cos5 = | cos(45−30)= | ||||
| 4 | 4 | 4 | 4 |
| 1 | √2 | √3 | √2 | 1 | √6+√2 | |||||||
= | ( | * | + | * | ) = ......... = | =P | ||||||
| 4 | 2 | 2 | 2 | 2 | 16 |