The scale factor for two similar triangles is 4 : 3. The perimeter of the smaller triangle is 12. What is the perimeter of the larger triangle?

Answer 1

since perimiter is a linear measurement, the ratio of the perimeter equals the ratio of the sides

if x is the larger perimeter,
x/12 = 3/4
4x = 36
x = 9

Answer 2

If sides of a triangle are 3,4, and 5 with a scale factor of 3, what are lengths of the similar triang