| sinx+sin2x+sin3x | π | ||
oblicz wartość argumentu dla x= | |||
| 2cosx+1 | 12 |
x= 15o
| a+b | a−b | |||
zastosujemy wzór: sina+ sinb= 2sin | *cos | |||
| 2 | 2 |
| x+3x | x−3x | |||
sinx + sin3x= 2sin | *cos | = 2sin2x*cosx
| ||
| 2 | 2 |
| 2sin2x*cosx+sin2x | sin2x( 2 cosx+1) | ||
= | = sin2x
| ||
| 2cosx+1 | 2cosx+1 |
| π | π | |||
zatem sin2x= sin2* | = sin | = 12
| ||
| 12 | 6 |