Answer:
A. 22.5 cm, 30 cm, and 37.5 cm
Step-by-step explanation:
If three sides of a triangle are in the ratio 3:4:5, then the lengths of the sides are 3x cm, 4x cm and 5x cm.
The preimeter of the triangle is the sum of the lengths of all sides, thus
[tex]3x+4x+5x=90\\ \\12x=90\\ \\x=\dfrac{90}{12}=\dfrac{30}{4}=7.5\ cm[/tex]
So, the lengths of the triangle's sides are
[tex]3x=3\cdot 7.5=22.5\ cm\\ \\4x=4\cdot 7.5=30\ cm\\ \\5x=5\cdot 7.5=37.5\ cm[/tex]
