Yes they are similar due to the AA similarity theorem and the SSS similarity theorem. The AA stands for "angle angle". We have a pair of angles that are congruent which allows us to conclude that the triangles are similar. Check out the attached image "Figure 1" to see the angles in question. Note the color coding.
The SSS similarity theorem comes into play when we take the ratios of the corresponding sides. So,
20/5 = 4
48/12 = 4
52/13 = 4
each division results in 4; each side of the larger triangle is 4 times larger than the smaller corresponding side. Check out Figure 2 to see how the sides pair up.
