Can I get some help with this question?

Let a=(1, 5) and b=(2,2) and let c=(x,0) with x >= 8/3 be a point along the x-axis.

(a) Find the maximum possible angle at c in the triangle abc.

(b) Find the maximum possible length for the shadow along the y-axis cast by the line

segment ab when a light is placed at point c.