AutoCAD Inventor :: Sketch Update Using WHILE Command

I am having a problem with a sketch not updating the parameters when using a "while / end while" command.

Basically if you have a right angled triangle (as attached) with one side and the angle doing the driving then I wish to update the sketch until the last side which is a reference dimension reaches a preset dimension.

I cannot get the updated sketch to read back into the while command to stop when the limit is reached. Instead it goes on an infinite loop until the sketch breaks.

I have used every update under the sun and can get nothing to work.

Trigonometry not an option as this is a basic example of what I wish to achive.

I have seen an example of this working but only for reading the iproperties so dimensions can change until a volume is reached.