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LOPTA R R lopta

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www.matematiranje.com<br />

1) Površina lopte jednaka je 225 π . Naći njenu zapreminu.<br />

P π<br />

= 225<br />

_____________<br />

V = ?<br />

4 3<br />

V = R π<br />

3<br />

4 3<br />

V = ( 7,<br />

5)<br />

π<br />

3<br />

V = 562,<br />

5π<br />

2) Preseci dve ravni i lopte imaju površine 49 π i 4 π , a rastojaje izmedju tih ravni koje<br />

su sa raznih strana centra lopte iznosi 9. Naći površinu lopte.<br />

P = 49π<br />

1<br />

P = 4π<br />

2<br />

h = 9<br />

________<br />

PL<br />

= ?<br />

Preseci lopte su krugovi, pa ćemo odstale naći r 1 i r 2 .<br />

2<br />

P1<br />

= r1<br />

π<br />

2<br />

49π<br />

= r1<br />

π<br />

r = 7<br />

1<br />

2<br />

P2<br />

= r2<br />

π<br />

2<br />

4π<br />

= r2<br />

π<br />

r = 2<br />

2<br />

2<br />

P = 4R<br />

π<br />

2<br />

225π<br />

= 4R<br />

π<br />

R<br />

2<br />

=<br />

225<br />

4<br />

225<br />

R =<br />

4<br />

15<br />

R =<br />

2<br />

R = 7,<br />

5<br />

Uočimo dva pravougla trougla (na slici) čije su hipotenuze R a katete za jedan x i r1 a za<br />

drugi y i r 2<br />

4

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