Sketch the region bounded by the semicircle y=sqrt(2x-x^2)

and the x-axis and then evaluate the given integral.........

then the class notes say therefore this is "a circle centred at (1,0) with radius 1.

how do you know this is a circle with radius one?

how do you know where it is centred?

starting a table of values is the only way I know to work out how to plot this