In one of my books there is a question:
"Problem: What is the trigonometric relationship between the length of the chord and the angle subtended at the centre?"
[tex]\theta[/tex] is the angle subtended at the centre.
Next to it is simply written:
[tex]2r \sin(\frac{\theta}{2}) = l[/tex]
I'm sure I wrote that; but I can't remember proving it.
Can anyone help?
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