I meassure the height from the triangle's left bottom to top and place it at the beginning of the new 5 impulse sequence. Now that we've probable made a first Elliott Wave impulse I take 2.618 of the first wave which lands around the top of the meassure stick. Then I make an assumption that the 1st wave will be equal to the 5th which is common in Elliott Waves.

Does that make sense? :)