[slijin]

In the sketch, create one triangle where you want to begin to pattern it. Fillet it appropriately, finish the sketch, then cut out the triangle. In the ribbon, select the Rectangular option under Patterns. Select the cut-out triangle, then switch to selecting direction for the pattern. Click a lateral edge along the way you want the pattern to go, then enter a number of instances to create (this includes the starting shape), and the spacing between the instances (the spacing between the starts of consecutive instances, not the space between the end of one instance and the start of the next).

This should not update any parameters, because all it does is replicate a feature with specified parameters.