2.ÎÑÅÂÀß ÑÈÌÌÅÒÐÈß

 

         Ïðåäñòàâëåíèå îá îñåâîé ñèììåòðèè íàì äàþò ñëåäóþùèå èëëþñòðàöèè.

     

 

              ðèñóíîê                                                       ðèñóíîê

Ãîãîëåâîé Íàòàëüè, 6á                                   Íèêèòèíà Âëàäèìèðà, 6á                                    Ïàðèæ

 

Äâå òî÷êè À è À1 íàçûâàþòñÿ ñèììåòðè÷íûìè îòíîñèòåëüíî ïðÿìîé à, åñëè ýòà ïðÿìàÿ ïðîõîäèò ÷åðåç ñåðåäèíó îòðåçêà ÀÀ1 è ïåðïåíäèêóëÿðíà ê íåìó. Êàæäàÿ òî÷êà ïðÿìîé à  ñèììåòðè÷íà ñàìà ñåáå.

 

 

 

 

        

 

 

 

 

Ôèãóðà íàçûâàåòñÿ ñèììåòðè÷íîé îòíîñèòåëüíî ïðÿìîé à, åñëè äëÿ êàæäîé òî÷êè ôèãóðû ñèììåòðè÷íàÿ åé òî÷êà îòíîñèòåëüíî ïðÿìîé à òàêæå ïðèíàäëåæèò ýòîé ôèãóðå. Ïðÿìàÿ à íàçûâàåòñÿ îñüþ ñèììåòðèè. Ãîâîðÿò òàêæå, ÷òî ôèãóðà îáëàäàåò îñüþ ñèììåòðèè.

ÓÏÐÀÆÍÅÍÈÅ 1. Íàéäèòå êàê ìîæíî áîëüøå ïðåäìåòîâ, èìåþùèõ îñü ñèììåòðèè â îêðóæàþùåé îáñòàíîâêå äîìà è íà óëèöå.

         ÓÏÐÀÆÍÅÍÈÅ 2. Îïðåäåëèòå, ñêîëüêî îñåé ñèììåòðèè èìååò êàæäàÿ èç äàííûõ ôèãóð?

 

 

 

 

 

 

 

 

 

 

ÎÒÂÅÒ

         À êàê æå ïîñòðîèòü ôèãóðó, ñèììåòðè÷íóþ äàííîé? Ïðåäñòàâèì, ÷òî l – îñü ñèììåòðèè. Ïîñòðîèì ëîìàíóþ À 1 1Ñ1, ñèììåòðè÷íóþ ëîìàíîé ÀÂÑ.

         1) Èç âåðøèí À è Â îïóñêàåì ïåðïåíäèêóëÿðû íà ïðÿìóþ l.

         2) Ïðîäîëæàåì èõ çà îñü ñèììåòðèè íà ðàññòîÿíèå, ðàâíîå äëèíå ñîîòâåòñòâóþùåãî îòðåçêà.

         3) Ñîåäèíèì ïîëó÷åííûå òî÷êè. Ëîìàííàÿ À1Â1Ñ1 – ñèììåòðè÷íà ÀÂÑ. (òî÷êà Ñ îñòàëàñü íà ìåñòå – îíà ñèììåòðè÷íà ñàì ñåáå)

 

                                                                                                                                               

                                                                                                                   1                                

                                                                                                 B                                      B1

        

                                                           A                                                                                                                  A1  

C

 
                                                                                                                      

                                                                                                                      

 

 

 

Ê ÎÃËÀÂËÅÍÈÞ

 

Ê ÏÓÍÊÒÓ 3