Առաջադրանք 123
ա) B(√2/2, √2/2)
բ) α=3π/4=135° B(-√2/2, √2/2)
գ)α=-π/4=45°, B(√2/2, -√2/2)
դ) α=-135°B(-√2/2, √2/2)
Առաջադրանք 124
ա) sin60°=√3/2 , sin30°=1/2 (1/2; √3/2)
բ) α=π/6=30° , (√3/2; 1/2)
գ)α=120° , (-1/2; √3/2)
դ) α=5π/6=150° , (-√3/2; 1/2) ⁄
Առաջադրանք 125
Լրացրեք աղյուսակը:
| 0° 0 |
30° π/6 |
45° π/4 |
60° π/3 |
90° π/2 |
120° 2π/3 |
135° 3π/4 |
150° 5π/6 |
180° π |
|
| sinα | 0 | 1/2 | √2/2 | √3/2 | 1 | √3/2 | √2/2 | 1/2 | 0 |
| cosα | 1 | √3/2 | √2/2 | 1/2 | 0 | -1/2 | -√2/2 | -√3/2 | -1 |
| tgα | 0 | √3/3 | 1 | √3 | – | -√3 | -1 | -√3/3 | 0 |
| ctgα | – | √3 | 1 | √3/3 | 0 | -√3/3 | -1 | -√3 | – |
Առաջադրանք 126
ա) sin9π/4
sin(α±2π)=sinα ⇒ sin9π/4= sin(π/4 ± 2π)= sinπ/4=√2/2
բ) cos19π/4
cos(α±2π)=cosα ⇒cos19π/4= cos(3π/4 ± 2π*2)= cos3π/4= -√2/2
գ) tg13π/6
tg(α±2π)=tgα ⇒ tg13π/6= tg(3√3 ± 2π)= tg3√3
դ) tg(-570°)
tg(α±2π)= tgα ⇒ tg(-570°)= tg(570-2*360)=tg150°= -√3/3
ե) sin(-11π/6)
sin(2π+α)=sinα ⇒ sin(-11π/6)= 1/2
զ) cos810°
cos(α±2π)= cosα ⇒ cos810°= cos(720+90)=cos90°=0