Problem with a triple integral in cylindrical coordinates

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Amaelle
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Homework Statement
look at the image
Relevant Equations
cylindrical coordinates
Good day
Triple integral over region A: integral of x dx dy dz where A is the set of (x, y, z) in R^3 with y^2 + z^2 - 2 <= x < -sqrt(2 - y^2 - z^2).

here is the solution
Typeset text defining sets B and C in R^3 via a paraboloid x = y^2 + z^2 - 2 and a sphere x^2 + y^2 + z^2 = 2, with the intersection condition rho^2 - 2 = -sqrt(2 - rho^2) solved to rho = ±sqrt(2) or rho = ±1.

Worked solution of a triple integral in cylindrical coordinates: a 3D sketch of a paraboloid bowl with the region A shaded, the substitution y = rho cos theta, z = rho sin theta, and the highlighted text stating rho = 1 is the only acceptable value, followed by the integral evaluated to -5/12 pi.
J just don't understand why the solution r=√2 has been omitted??
many thanks in advance
best regards!
 
Easiest thing to do is make a drawing.
Plane z = 0 :

Graph in the xy-plane of a blue circle of radius about 1.41 centred at the origin and a red parabola y = x^2 - 2, intersecting at four points.
 
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BvU said:
Easiest thing to do is make a drawing.
Plane z = 0 :

View attachment 277967
thanks a million your graph with the explantion of Charle link is just awsome!
 
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