Answer: masculine
1. Dicho
2. Comenzado
3. Descubierto
4. Corrido
Feminine
5. Tenida
6. Vista
7. Dormida
8. Traída
Explanation: In the past participle in spanish, the verbs of the first conjugation (those ended in -AR) end with -ado, and the verbs of the second conjugation (-ER) end with -ido. The verbs of the 3rd conjugation (those ended with -IR) end with -ido too.
They need to be written according to the genre and number too, so if it is feminine instead of IDO we end the verbs with IDA, and instead of ADO we end verbs with ADA (for example, atado/atada).