ISOMERISM IN OCTAHEDRAL

Mr J : Sir, do you still remember about cis-trans isomerism in complex compound ?

Mr G : Hm....blank for a while hhh.. i'm forget sir J. Then i fall in sleep.

Mr J : yah....

a couple minutes later....

Mr J : Sir, do you wanna see this ? ( he shows me the paper about isomerism in octahedral ). How do you think,which one is cis ?which one is trans?

Mr G : Hoah...(yawning)... Hm, i think this is trans- sir...

Mr J : But, take a look this one, this is cis in my opinion, because of my view it has same ligands.

Mr G : Ok, Lets discuss it ( I am fresh now )hhhh

I have a good reference : chem.libretexts.org

a. MA₅B

b. MA₄B₂

c. MA₃B₃

So the ligands those are 180 degrees to each other are said to be trans, while ligands those 

are 90 degrees to each other are to be cis. 

Isomerism,,yup this one that i need to recall back, because i'm in my comfort zone,then some memory about chemistry slowly but sure dismiss from my head.