Question

The sum of the circumference of 2 circles is 38pie cm. & the sum of their areas is 193pie cm^2. how do we calculate the radii of the circles?

Answer 1

the circumference formula is 2rpi
and the area formula is pir2 where r2 signe r square

Answer 2

sorry but what do we do first for the workings?

Answer 3

C=2pi r x 2 (since there are 2 circles)

38pi = 4pi r
38pi/4pi=4pi/4pi r
38/4=r
9.5 =r


A=pi r^2 x 2 (since there are 2 circles)
193pi=2pi r^2
193pi/2pi=2pi/2pi r^2
96.5= r^2
(96.5)^1/2=r
9.8=r

that is only an approximation!! i hope i get it..

Answer 4

2pir1 +2pir2=38pi from this we result r1 +r2 =19
pi(r1)2 +pi(r2)2=193pi from thie result (r1)2 +(r2)2 =193

Answer 5

hope that after this will be easy to make the calcule

Answer 6

i've checked the answer and the radii is 7cm and 12cm

Answer 7

- sign r1 = a
r2 =b
so than you get

a+b=19
a2+b2=193 - where a2 is a square and b2 is b square

Answer 8

and now you need to solve this system for a and b

Answer 9

ok ?

Answer 10

um so we get 2 equations..
a+b=19
a^2 (a squared)+b^2 (b squared)=193
?

Answer 11

yes

Answer 12

how do we continue from here?

Answer 13

from a+b=19 you get a=19-b so this substitute in the second equation and will get b=?
after you will can calcule the a

Answer 14

:o yeah. thanks jhonyy :D

Answer 15

my pleasure

Answer 16

thank you for the medal

Answer 17

:) u deserve it haha.

Answer 18

ok good luck

bye