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Math Help - How far is a chord of length 8 cm from the centre of a circle of radius 5 cm?

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    How far is a chord of length 8 cm from the centre of a circle of radius 5 cm?

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  2. #2
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    Quote Originally Posted by Lalis View Post
    A chord across a circle forms an isosceles triangle by joining the centre of the circle
    to the two endpoints of the chord.

    An isosceles triangle in turn is formed of two back-to-back identical right-angled triangles.

    Now you may use Pythagoras' theorem, since half of the chord is 4 units long.
    That gives one of the perpendicular sides of one of the identical right-angled triangles.
    The hypotenuse is the radius.

    All that remains is to calculate the other perpendicular side using Pythagoras' theorem.
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