I think that you need to measure the sides of the triangle
for example you get the following result
side 1 = 10 cm
side 2 = 8 cm
side 3 = 6 cm
Scale factor = 1/2, divide all the lengths by 2.
then
side'1 = 5 cm
side' 2 = 4 cm
side' 3 = 3 cm
The new triangle will be smaller than the original
