Question 1169133
Try to draw and label the description.  If y is how tall the shed, x is how far from ground level of shed to point A, and finding that angle of elevation from point B is 8 degrees, then:

{{{system(tan(20)=y/x,tan(8)=y/(x+30))}}}


Substitute for x and solve for y.

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{{{y=(3*tan(8)tan(20))/(tan(20)-tan(8))}}}