Question 929622
With side ratio 3:5:7 , first add the numbers together.
This will give us a denominator to find fractional parts.
3+5+7 = 15
The shortest side will be 3/15 * 12 = 36/15 = 2.4
Then next side will be 5/15 * 12 = 60/15 = 4
The last side will be 7/15 * 12 = 84/15 = 5.6

Notice that 2.4:4:5.6 is equivalent to 3:5:7
2.4:4:5.6 , multiplying each element by 10
gives us 24:40:56
Divide each by 8 and we get
 3:5:7