y = √(a2 – x2)
Squaring both sides
⇒ y2 = a2 - x2
⇒ x2 + y2 = a2
This is equation of circle having center as (0, 0) and radius a
Now in y = √(a2 – x2) -a ≤ x ≤ a and y ≥ 0 which means x and y both positive or x negative and y positive hence the curve y = √(a2 – x2) has to be above X-axis in 1st and 2nd quadrant
x = 0 is equation of Y-axis and x = a is a line parallel to Y-axis passing through (a, 0)
Using uv rule of integration where u and v are functions of x