"We will go over there, even though we are tired."
Translation:On ira là-bas, bien qu'on soit fatigués.
You use être with "fatigué". Moi, je suis fatiguée. In French it is a state of "being," unlike hunger (faim), thirst (soif), hot (chaud), cold (froid)... with those descriptions you would use "avoir."
There is no easy way to know, it's just one of those things that you have to memorize since these things are expressed differently in French.
When "on" refers to "one" in general it stays singular and masculine. However, when the people involved are specified you can make the accords. Hence fatigués, fatiguées, and fatigué are all accepted as correct.
Here is what the Académie Française has to say on the matter:
Il arrive pourtant que on ne désigne pas les hommes en général, des personnes indéterminées, mais telle ou telle personne : dans ce cas, l’accord se fait tout naturellement en genre et en nombre.
C’est le sens qui commande, et le goût. On s’était fâchés ; On s’est séparées à regrets ; On est allés ensemble jusqu’au bout du chemin... ne sont donc pas des tournures fautives.
No, you cannot mix "on" and "nous" in the same sentence when you are referring to the same group of people. In fact, they shouldn't be mixed in the same paragraph.
"Nous" is more formal but it is appropriate in all contexts.
"On" is more casual and more common in oral language.
Là-bas means "over there" http://larousse.fr/dictionnaires/francais-anglais/l%C3%A0-bas/45696
(It can also mean "down there".)
That is bizarre. If it happens again could you please get a screenshot?
"On ira là-bas bien que l'on soit fatigués" is also correct, but your answer should have been accepted.
To post a screenshot here, you'll have to upload it to a hosting site like Imgur. Then right click on the picture and click "Copy image address" (or the equivalent in your browser). Then, here, type !(Pasted image address), replacing "Pasted image address" with what you just copied. Make sure not to leave any spaces.
It seems I consistently trip up on the use of "aller + infinitive" versus the simple present, since I never really figured there was a true difference between them in meaning. But then I got this wrong for writing "On va aller" rather than "On ira." Can someone break down the difference for me?