The circle 
passes through the points 
and 
, and its centre lies on the line 
.
Write down the centre, radius and equation of the circle . Help yourself with a sketch.
Find all points 
on the circle for which the area of triangle 
is equal to 
.
A trapezium 
with base 
should be inscribed on the plane . Vertex 
should lie in the first quadrant on the line 
. Write the vertices and 
and calculate the area of the trapezium .
Among all triangles that are inscribed circles and have one side , choose the triangle with the largest area. Write down its vertex 
.
.
