Find the volume of the solid whose base is a triangular region with vertices (0, 0), (2, 0) and (0, 2) if the cross-sections perpendicular to the Y -axis are squares.
My problem is that I can't figure out how the shape will be like... I need some images.
What I think is
Volume = $\int\limits_a^b Area\,dy$
=$\int\limits_a^b base^2\,dy$
= $\int\limits_0^2 y^2\,dy$
= $\frac{8}{3}$
?????
[2nd Edit]
Should be like this?
Volume = $\int\limits_a^b Area\,dy$
=$\int\limits_a^b base^2\,dy$
= $\int\limits_0^2 x^2\,dy$ ; Since y = -x +2 or x = 2-y
= $\int\limits_0^2 (2-y)^2\,dy$
= $\int\limits_0^2 y^2-4y+4\,dy$
= $[\frac{y^3}{3} - 2y^2 +4y]$ from 0 to 2
= $\frac{8}{3}$
If the cross-sections perpendicular to the $Y$-axis are squares, then we know that the cross-sectional area at a height $y$, will be given by the square distance from the Y-axis to your line $y=2-x$. This distance is just $x$. If we integrate over the $y$-direction we can now find the volume of your object.
So, volume = $\int_{0}^{2} x^2 dy$. Here we have the mismatch of a variable in $x$ and our integration being over $y$, we so we the equation of the line to substitute $x = (2-y)$, and we find that the volume is $\int_{0}^{2} (2-y)^2 dy$.
I think you can take it from here.