To work out the answer to part b, you have to subtract the angle given at the centre from the other angle on the outerside of the snowflake. This will then need to be divided by 2 to get the answer of each pointed end of the smowflake. Therefore, if the centre angle is 33 degrees and the other angle on the outerside is 63 degrees and the two opinted edges are marked as the angle b - you should do 63-33 = 30. Then divide this by 2 to get the answer ie 15 degrees. Hope that is correct!