Sketch the region and x-axis. Find the area of the region using integration



Square both sides


y2 = 4 – x2


x2 + y2 = 4


x2 + y2 = 22


This is equation of circle with center origin and radius 2


Now in -2 ≤ x ≤ 2 and y ≥ 0 which means x and y both positive or x negative and y positive hence the curve has to be above X-axis in 1st and 2nd quadrant


Hence the graph of will be graph of circle x2 + y2 = 22 lying only above X-axis


Now equation of X-axis is y = 0


To find point of intersection of circle with X-axis put y = 0 in circle equation


x2 = 4


x = ±2


Hence the intersection points with X-axis are (-2, 0) and (2, 0)


Hence the area is shown as below



Now let us find the area



Integrate from -2 to 2



Using uv rule of integration where u and v are functions of x



Here and v = 1


Hence







But






We know that







Hence area is 2π unit2


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