cos2x | ||
b) | ≤1 , x∊<0,2π>. | |
cosx |
sinx | π | |||
sin2x+cos2x− | =cos2x−sin2x i cosx≠0⇔x≠ | +kπ, k∊C | ||
cosx | 2 |
sinx | ||
⇔2sin2x− | =0 | |
cosx |
π | π | |||
x=kπ v x= | +kπ i x≠ | +kπ , k∊C | ||
4 | 2 |
cos(2x) | π | ||
≤1 i x∊<0,2π> i x≠ | +kπ | ||
cosx | 2 |
2cos2x−1 | |
≤1 | |
cosx |
2cos2x−1 | |
−1≤0 | |
cosx |
2cos2x−1−cosx | |
≤0 | |
cosx |
1 | ||
t=− | lub t=1 | |
2 |
1 | ||
t∊<−1,− | > lub t∊(0,1) | |
2 |
1 | 3π | |||
cosx∊<−1,− | > lub cosx∊(0,1> i x≠U{π}2} i x≠ | ⇔ | ||
2 | 2 |
π | 2π | 4π | 3π | |||||
x∊<0, | ) ∪< | , | >∪( | ,2π> | ||||
2 | 3 | 3 | 2 |