The smaller of two similar triangles has a perimeter of 20cm (a+b+c=20cm). The lengths of the longest sides of both triangles are in proportion 2:5. What is the perimeter of the larger triangle? Please explain.

1 Answer
Dec 8, 2015

color(white)(xx)50

Explanation:

color(white)(xx)a+b+c=20

Let sides of larger triangle are a', b', and c'. If similarity proportion is 2/5, then,
color(white)(xx)a'=5/2a,
color(white)(xx)b'=5/2b,
andcolor(white)(x)c'=5/2c

=>a'+b'+c'=5/2(a+b+c)
=>a'+b'+c'=5/2color(red)(*20)
color(white)(xxxxxxxxxxx)=50