I have two problems to finish my worksheet and was hoping for some help.

First one is...find the smallest positive angle from the positive x-axis to the vector OP that corresponds to (3,3).

I think it is pi/4 since that is the smallest angle and still positive.

Second one is...determine m such that the two vectors 3i-9j and mi+2j are orthogonal.

I could apply the dot product to it but the orthogonal makes me think I may not really be thinking about it the right way.