(あく) (VI) A door opens.
ける(あける) (VT) I open a door.
ける(ひらける) Something has been spread out or opened up. Like ひらく, ひらける is more figurative. You wouldn’t use them about doors or windows. ひらける is like, a vista opened up before your eyes when you got to the top of the mountain. Or China has opened up to foreign investment.
が and を 開く:ひらく:this word is fucked up – because it is spelled exactly the same as 開く (a door opens), but a) pronounced differently (ひらく not あく) and it’s TRANSITIVE, whereas あく is INTRANSITIVE. Just nuts, right?!?! Also, by the way, the meaning is different:ひらく is more broad and figurative:someone hosts or holds a party or event. Opens his house to the public. Flower petals open. A space figuratively opens up between the fastest runner and the runners behind her in the race.