Two identical-sounding verbs share this shape. One is being on the receiving end of a blow — 친구들하고 싸워서 맞고 들어오잖아요 (they come home having been beaten in a fight), 시위대에 잡혀서 맞거나 — and by extension receiving an injection: 백신은 잘 생각해서 맞으십시오 (think it over carefully before you get the vaccine). The other is being right or correct, which is what 예를 들어서 맞아 and 맞는 건 줄 are. Only context separates them.