Answer: 23 cm
Step-by-step explanation:
Given
[tex]a=3.5\ cm\\b=9.4\ cm[/tex]
Triangle in the figure is right-angled triangle. Therefore, Pythagoras theorem can be applied. Suppose the unknow length of the triangle is x
[tex]\Rightarrow x^2=a^2+b^2\\\Rightarrow x^2=3.5^2+9.4^2\\\Rightarrow x^2=12.25+88.36\\\Rightarrow x^2=100.61\\\Rightarrow x=10.03\ cm[/tex]
The perimeter of triangle is the sum of the lengths of sides.
[tex]\text{Perimeter }P=3.5+9.4+10.03\\\Rightarrow P=22.93\ cm\approx 23\ cm[/tex]
