How many vertices does a 3D L shape have?

[Walthams]

How many vertices does a 3D L shape have?


My dd said the answer is 10. Is she correct? Or is the answer 12? Do we not count the 'inward' going corners as vertices?

How about corners in 2 D shapes? Do the 'inward' going corners count as corners or not?

Thanks very much for your help.

[Guest55]

A vertex is a point where edges or faces meet, so yes concave 'points' are vertices.

[Walthams]

Thank you. My dd said at school the teacher told them the inward going 'corners' don't count as corners!!!! I wonder if they taught them wrong or it's her memory playing tricks, buts she says she is sure the teacher said so...

[Tinkers]

Is this a primary school teacher?

I had to correct the maths ‘knowledge’ taught by a couple of DDs primary school teachers in the past.