| sinx | cosx | ||
+ | =4sin2x zał. sinx≠0 i cosx≠0 | ||
| cosx | sinx |
| sin2x+cos2x | |
=4sin2x | |
| sinxcosx |
| 1 | |
=4sin2x | |
| 0,5sin2x |
1≠0,
wtedy
tgx+ctgx=4sin2x /*sinxcosx ⇔ sin2x+cos2x= 2sin2x * 2sinxcosx ⇔
⇔ 1=2sin2xcos2x /:2 ⇔ sin4x=12 ⇔ 4x=π6+2kπ ⋁ 4x=π−π6+2kπ ⇔
⇔ x=124π+12kπ ⋁ x=524π+12kπ ⇔
⇔ x=124π(1+12kπ) ⋁ x=124π(5+12kπ) . ...