Extracted text: 1) Two L6 x 3½ x '½ steel angles, put long sides back to back, form a column. The column is pin connected at the base and top, and is 28 ft. high. Determine the critical buckling load, Per, with E = 29 x 10' ksi. (You need Ix and Iy. There is some symmetry to locate the centroid, but you need to know the x 's. These can be found in the text reference tables.)