• Apologies for the issue with a bizarre redirect on the site earlier today. There was a large server update and an error in an IP address had the traffic routing wrongly. No hacking or anything nefarious and nothing to worry about. Sorry for any stress/anxiety caused. Very best wishes - SF Admin

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  1. NoneKnowNothingness

    Railroad Drawbridge Problem for Trigonometry Students

    A railroad drawbridge over a canal is to pivot upward, so boats can pass under it. For trig students this is a good problem. The end-plate of the bridge span, where it lifts away from the rest of the track, cannot be due vertical in its rest position. If it were, the plate would jam as the span...
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