ANSWER
3:5
EXPLANATION
The given similar octagons have areas 9 m² and 25m² .
Let the scale factor of their side lengths be in the ratio:
m:n
[tex] {( \frac{m}{n}) }^{2} = \frac{9}{25} [/tex]
We take square root of both sides to get;
[tex] \frac{m}{n} = \sqrt{ \frac{9}{25} } [/tex]
We simplify the square root to get
[tex] \frac{m}{n} = \frac{3}{5} [/tex]
Therefore the scale factor of their side lengths is 3:5
