The Law of Sines

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Hook

The surveyor's river problem

Right triangles are tidy — but the real world is full of OBLIQUE triangles, with no right angle in sight. A surveyor needs the distance across a river but can only walk along their OWN bank. They can't measure the width directly. Two angles and one side are all they get. The Law of Sines turns that scrap of information into the missing distance — and works on ANY triangle.