Equivalent Line Angle Structures? Are the following equivalent structures for 2,2-dimethylpropane?


I think so, because my rendering simply rotates the cross 45 degrees! 

Also, regarding 3,3-diethylpentane, are these both equally valid structures? My rendering seems to look way different but filling in the carbons and hydrogens, both appear correct:
a) yes, those are equivalent structures of 2,2-dimethylpropane

b) yes, those are equivalent structures of 3,3-diethylpentane