– misol. O markazli har xil radiusli ikkita doira berilgan. Kichik doiraga o`tkazilgan urinmani katta doira bilan hosil qilgan kesmasi 32 sm. Agar halqani eni 8 sm bo`lsa katta doira radiusini toping.
Yechish: Shartga ko`ra AB = 32 sm, CD=8sm,
Shuningdek OC AB. Katta doira radiusi-
ni R desak, u holda OCB to`g`ri burchakli
uchburchakdan:
OB2 = OC2 + CB2 yoki R2= (R – 8)2 + 162 , R = 20 sm.
Javob: 20 sm
6 – misol. Umumiy vatarga tiralgan ikki doirani mos yoylari 600 va 1200. Doiralar yuzalari nisbatini toping.
Y
echish: O1B = r, O2B = R deb belgilaymiz.
Shartga ko`ra < A O1B = 1200 , 2B = 600.
Ikki aylana markazlari orasidagi O1O2 kesma AB ga perpendikulyar, u holda
, bundan R = 2BC, demak
= R2 : r2 = 3 : 1 Javob:_3:1__7-_misol.'>Javob: 3:1
7- misol. Yoyi 1200 , perimetri R bo`lgan segment yuzasini toping.
Yechish: R doira radiusi. Bundan ACB yoyni aniqlaymiz:
= · 1200= πR .
AOB uchburchakdan AB = 2 R sin 600 = R Shartga ko`ra AB+ =R, demak
R + R =R, bundan R= .
S segmentni yuzi sektorni yuzidan
OAB uchburchak yuzini ayirishdan hosil bo`lgan son bo`ladi.
Shuning uchun
S = πR2 – .
Javob:
8 – misol. Radiuslari R va r bo`lgan ikki aylana tashqi o`rinadi. Nuqtalari orasidagi kesmasini toping.
