The triangle is
3 arrow 120
The secret is that the turtle has to turn through a full circle (360 degrees) to get back to point the same way - so if you want a pentagon (for example) with 5 turns each turn will have to be 360/5=72 so
5 (forward turn72)
Of course in the later puzzles you can store any new shapes as smilies rather than their actual shape.
One of the final turtle puzzles still stumps me from time to time
If all else fails the exact solutions are on my web site.
Hope this helps.