Volume of a tilted cylinder

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Suppose I have a tilted cylinder of length l inclined to the horizontal by an angle of $\theta$ then it's volume comes out to be same as that of a straight cylinder of height $l\sin\theta$. I tried to find a formal proof for this online but all I got was vague analogies of a stack of coins and pile of discs. Any proof using single variable calculus will be appreciated.

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The Cavalieri's principle as suggested by Arthur is the good idea. I will hint an alternative: wlog suppose that the centers are along the line $z = x\sin\theta_0$. Do a change of coordinates transforming the tilted cylinder in a cylinder. Obviously, in the new coordinates $u,v,w$ $$u = \cdots$$ $$v = y,$$ $$w = z.$$