"His parents must be contacted."
Translation:Il faut contacter ses parents.
You have translated "contacted" with an infinitive: "contacter." "Ses parents doivent être contactés" is accepted.
so is 'contactes' the past partiple, made plural so that it agrees with the subject since we used etre and not avoir?
since we used etre and not avoir?
No. This is actually in the passive voice. Same construction in English: être (to be) + past participle. In the passive voice, the past participle in French will always agree in gender and number with the subject.
How does his parents must be contacted, ie. Someone must contact them, equate to him doing the contacting? I don't understand how this translates top mean the same thing
Remember that "il faut" is impersonal. It doesn't matter who does the action. It just must be done.
- Il faut contacter ses parents = His parents must be contacted
- Il doit contacter ses parents = HE must contact his parents
For some reason I always thought that "il faut" needed to be "il faut que" (plus subjunctive.) Is simple "il faut" used a lot?