Newton's 2nd Law/Coefficient of friction

[aces9113]

Homework Statement

In the figure a sled being held on an inclined plane by a cord pulling directly up the plane. The sled is to be on the verge of moving up the plane. In the lower figure data is plotted with the magnitude F required of the cord's force on the sled is plotted versus a range of values for the coeffient of static friction μs between sled and plane. F1 = 10.50 N, F2 = 26.25 N, and μ2 = 0.290. At what angle θ is the plane inclined? (deg)
http://nplq1.phyast.pitt.edu/res/sc/gblanpied/courses/usclib/hrw8/hrwpictures/hrw8c6f028.jpg
http://nplq1.phyast.pitt.edu/res/sc/gblanpied/courses/usclib/hrw8/hrwpictures/hrw8c6f034.jpg

Homework Equations

The Attempt at a Solution

I've tried pretty much everything i can think of on this problem and can't seem to get any answer that makes sense. I tried to set the acceleration equal to zero but i kind of think that in order to find the angle i would need the greatest static friction possible but i don't really know how to do that.

 

[dimpledur]

Cannot see the figure as it requires a login ID.

 

[aces9113]

I submitted the chart as a document. Hopefully that works. The other one can be accessed here: http://www.google.com/imgres?imgurl...JWWCA&esq=1&page=1&ndsp=18&ved=1t:429,r:0,s:0

 

[aces9113]

except the angle is not 20 deg but only theta in my picture

 

[aces9113]

Can someone please help? I think I've fixed the link to the pictures and i still need assistance if possible

 

[ashishsinghal]

there is no figure...