Funkcje odwrotne
Zenon: Witam. Prosze o pomoc w trzech przykladach:
Oblicz: arccos(cos16π/5)
sin(2arcsin(√7/2√2)
tg(1/2arcsin(5/13))
Pozdrawiam
4 lis 18:06
Mila: 1) arccos(cos16π/5) =α i α∊<0;π>
| | 16π | | 6π | | 6π | |
cos16π/5=cos( |
| −2π)=cos( |
| )<0 i kąt |
| jest kątem III ćwiartki |
| | 5 | | 5 | | 5 | |
| | 6π | | π | | π | | 4π | |
cos |
| =cos(π+ |
| )=cos(π− |
| }=cos |
| |
| | 5 | | 5 | | 5 | | 5 | |
| | 4π | | 4π | |
arccos(cos16π/5)=arccos(cos |
| )= |
| |
| | 5 | | 5 | |
2)
4 lis 18:39
4 lis 18:53
pigor: ... np. tak :
1)
arccos(cos165π)= α=? ⇒ cosα= cos(
165π) i
0< α< π ⇒
⇒ α= −
165π+2kπ i k=2 ⇒
α= −3
15π+4π=
45π ∊(0;π) ;
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
| | √7 | | √7 | | √7 | |
2) sin(2arcsin( |
| ))= 2sin(arcsin |
| )) cos(arcsin |
| ))= |
| | 2√2 | | 2√2 | | 2√2 | |
| | √7 | | √7 | | √7 | | 7 | |
= 2* |
| √1−sin2(arcsin |
| ) = |
| √1− |
| = |
| | 2√2 | | 2√2 | | √2 | | 4*2 | |
| | √7 | | 1 | | √7 | | 1 | | √7 | |
= |
| √ |
| = |
| * |
| = |
| . ...  |
| | √2 | | 4*2 | | √2 | | 2√2 | | 4 | |
4 lis 19:27
pigor: ... no i przykład
| | 1−cos(arcsin513) | |
3) tg(12arcsin513)= |
| = |
| | sin(arcsin513) | |
| | 1−√1−sin2(arcsin513) | | 1−√1−(513)2 | |
= |
| = |
| = |
| | 513 | | 513 | |
| | 13−√132−52 | | 13−√169−25 | | 13−12 | | 1 | |
= |
| = |
| = |
| = |
| . ... |
| | 5 | | 5 | | 5 | | 5 | |
4 lis 19:42
Mila: Witam Pigor, trochę inaczej to liczę, ale tak samo wychodzi. Pozdrawiam.
4 lis 21:21
pigor: ... fajnie, dzięki już chyba wiem co jest grane z tymi arcusami . ...
4 lis 21:35