I'll be making a post on this later tonight.

]]>corners of this curved quatrilateral, then we can procede.

By you coming up with these (x,y) positions where the 60 degrees

works, this will further explain the problem, so there is no

uncertainty as to what you need because the we can draw

straight lines for those two sides of the shape. So get to work and

report back to us.]]>

A Lorry has a downwards wiping windscreen Wiper on a 40cm long metal arm. The rubber wiper part is at the end of the arm and is an articulate double module that alters in length during motion. The rubber alters between 30cm and 20cm, during a wiping "sweep" of the glass.

The full angle of the sweep is 60 degrees.

The bottom end of the rubber follows a path according to the equation

y = 1/30x (x-10* square root of 3)

The upper end of the rubber follows a path according to the equation:

y = 1/15 (x-5*square root of 3)^2 + 25

And we need to calculate the area of glass cleared in one full sweep of the arm.

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