Suppose right triangle ABC has one acute angle 47º. Suppose also that right triangle DEF has an acute angle 43º. How are triangles ABC and DEF related?

Its very simple

47 and 43 are related because its an acute angle

We notice that 47+43=90

we know that all angles are adding to 180

since they are both right triangles, one angle is 90

therefor the angles of both triangles are 47,43,90

that means the triangles are similar and their sides are in the same ratio