First off, an equilateral triangle is a triangle in which all three sides have the same length. Why does your user need to enter a height if it's irrelevant - the three sides are all base long, aren't they?
Secondly, don't use int.Parse to process user input = use int.TryParse instead, and report input problems to the user instead of your app crashing.
Then just work out the three points: for a triangle like this:
The top point X is the length of a side / 2, and it's Y is simply worked out using Pythagoras from that and the length of a side:
Y = sqrt(L * l - ( L * L / 4))