There is another easy way that doesn't require tangency constraint and can be therefore more robust: just draw a closed 5 sides polygon, like an irregular pentagon, then draw a "star" connecting the mid point of each side of the pentagon. Force equal length on the 5 edges of the poly and then force equal length on the 5 stars segments. You can now draw circles from the pentagon vertexes with a radius up to the mid point of the pentagon edge, and you're done. No tangent required, just a bit of construction.
