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I'm solving this problem in mechanics,

Two cylinders A and B, weighing 100 lb and 200 lb respectively, are connected by a rigid rod curved parallel to the smooth cylindrical surface shown in Fig. P-329. Determine the angles α and β that define the position of equilibrium.

Fig. P-329

I already understood that the relation between $\beta$ and $\alpha$ is $\cos \alpha = 2 \cos \beta$ by doing summation of moment with respect to O and equating to 0. What I don't get is how come the angle from this picture becomes 90 degrees?

enter image description here

Vilmar Cabañero
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1 Answers1

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It's given by the question. If you pay attention to the original image, you'll see that the internal angle ($180−\alpha−\beta$) has the classic right-angle symbol.

enter image description here Source

Wasabi
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