please answer this with workings out please
Two circular discs are touching. The diameter of the larger disc is seven times that of the smaller disc, and the distance between their centres is 28cm.
What is the diameter of the smaller disc?
thanks to anyone smart enough to work this out lol ; )
2007-08-05 15:05:08 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Diameter of small disc = d
Diameter of large disc = 7d
Assume discs are lying flat with edges touching.
3.5d + 0.5d = 28
4d = 28
d = 7
Diameter of smaller disc = 7 cm
2007-08-05 21:56:39 · answer #1 · answered by Como 7 · 0⤊ 0⤋
The distance between the centres is equal to the sum of the radii. If the diameter of the larger is 7 times longer, so is its radius. So r + 7r = 28
8r = 28
r = 28/8 = 7/2
d = 2r = 7
2007-08-05 22:12:48 · answer #2 · answered by hayharbr 7 · 0⤊ 0⤋
R1 = R2/7
R1+R2=28
R2*(8/7) = 28
R2=28*7/8= 49/2
R1 = 28/8 = 7/2
2007-08-05 22:15:32 · answer #3 · answered by telsaar 4 · 0⤊ 0⤋