Show ∆ABC and ∆DEF are similar.

I measure the angles of both triangles
and found that all of angles in ∆ABC are congruent to the angles in ∆DEF.

All of the side lengths in ∆ABC are proportional to the side lengths in ∆DEF.

The triangles are similar.

m∠A = 90°

m∠B = 37°

m∠C = 63°

m∠D = 90°

m∠E = 37°

m∠F = 63°

∆DEF side lengths

∆ABC side lengths

1
2

=

2
4

=

2.25
4.5

=

1
2

∆ABC ∼ ∆DEF