Stretching Equilateral triangle in dynamic blocks

[wael6URAQ]

I need  to create A dynamic block which allows to stretch an equilateral triangle by 1 grip of one of the equal sides and a user value for third side.

I managed to create this using Constraints but I need to create it by parameters but it didn't work

can any one help.

[Libbya]

An equilateral triangle has three equal sides.  An isosceles triangle has two equal sides. 

I don't think that can be achieved using only dynamic parameters/actions and operate in the way you describe.

[wael6URAQ]

sorry my mistake it is an isosceles  triangle but you know what I mean :).

Ok If So 

Is there a way to coincide dimension line to move with the constrained lines??

[h_s_walker]

You will probably need to use dimensional constraints as the shape of the triangle which change depending on what your base length is. See the image below