You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
ð³âíÿííÿìè ïåðøîãî ñòåïåíÿ. Öå îçíà÷àº, ùî ïðÿì³é â³äïîâ³äàº<br />
ð³âíÿííÿ ïåðøîãî ñòåïåíÿ.<br />
Ñïðàâåäëèâî ³ îáåðíåíå òâåðäæåííÿ.<br />
Òåîðåìà 4.3.1. Áóäü-ÿêå íåâèðîäæåíå ð³âíÿííÿ ïåðøîãî<br />
ñòåïåíÿ<br />
Àõ +Âó +Ñ = 0 (A 2 + Â 2 ≠ 0) (4.3.3)<br />
ÿâëÿº ñîáîþ ð³âíÿííÿ ïðÿìî¿ ë³í³¿ íà ïëîùèí³ Îõó (çàãàëüíå<br />
ð³âíÿííÿ ïðÿìî¿ ë³í³¿).<br />
Äîâåäåííÿ.<br />
1. Íåõàé ñïî÷àòêó Â≠0. Òîä³ ð³âíÿííÿ (4.3.3) ìîæíà<br />
çîáðàçèòè ó âèãëÿä³:<br />
A C<br />
y =- x<br />
B<br />
- B<br />
. (4.3.4)<br />
Ïîð³âíþþ÷è ç (4.3.2), ìè îäåðæèìî, ùî öå º ð³âíÿííÿ<br />
A<br />
ïðÿìî¿ ç êóòîâèì êîåô³ö³ºíòîì k =- ³ ïî÷àòêîâîþ îðäèíàòîþ<br />
b =- .<br />
B<br />
C<br />
B<br />
2. Íåõàé òåïåð Â=0. Òîä³ À ≠ 0 ³ ð³âíÿííÿ (4.3.3) áóäå<br />
ìàòè âèãëÿä:<br />
Àõ + Ñ =0,<br />
çâ³äêè<br />
C<br />
x =- . (4.3.5)<br />
A<br />
гâíÿííÿ (4.3.5) ÿâëÿº ñîáîþ ð³âíÿííÿ ïðÿìî¿, ÿêà ïàðàëåëüíà<br />
â³ñ³ Îó ³ â³äñ³êຠíà â³ñ³ Îõ â³äð³çîê a =- .<br />
C<br />
A<br />
Îñê³ëüêè óñ³ ìîæëèâ³ âèïàäêè âè÷åðïàí³, òî òåîðåìó<br />
äîâåäåíî.<br />
4.3.2. Êóò ì³æ äâîìà ïðÿìèìè<br />
Ðîçãëÿíåìî äâ³ ïðÿì³ (íå ïàðàëåëüí³ îñ³ Îó), ÿê³ çàäàí³<br />
¿õí³ìè ð³âíÿííÿìè ç êóòîâèìè êîåô³ö³ºíòàìè (ðèñ. 4.19):<br />
Ðèñ. 4.19<br />
(I) y= k 1 x+b 1 , (4.3.6)<br />
äå k 1 =tgϕ 1 ³<br />
(II) y = k 2 x+b 2 , (4.3.7)<br />
äå k 2 =tgϕ 2 .<br />
Ïîòð³áíî âèçíà÷èòè êóò θ ì³æ íèìè. Éîãî ìè áóäåìî<br />
ðîçóì³òè ÿê íàéìåíøèé êóò, ùî â³äðàõîâóºòüñÿ ïðîòè õîäó<br />
ãîäèííèêîâî¿ ñòð³ëêè, íà ÿêèé äðóãà ïðÿìà ïîâåðíåíà â³äíîñíî<br />
ïåðøî¿ (0 ≤θ< π).<br />
Öåé êóò θ (ðèñ. 4.19) äîð³âíþº êóòó ÀÑ òðèêóòíèêà<br />
ÀÂÑ. Äàë³, ç åëåìåíòàðíî¿ ãåîìåò𳿠â³äîìî, ùî çîâí³øí³é<br />
êóò òðèêóòíèêà äîð³âíþº ñóì³ âíóòð³øí³õ êóò³â, ÿê³ ç íèì<br />
íå ñóì³æí³. Òîìó<br />
ϕ 2 =ϕ 1 +θ<br />
àáî<br />
θ= ϕ 2 −ϕ 1,<br />
108 109