How to Find the Radius of a Circle From a Chord

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Dealing with parts of a circle, such as radius and chord, are tasks that you may face in high school and college trigonometry courses. You also may have to solve these types of equations in career fields such as engineering, design and landscaping. You can find the radius of a circle if you have the length and height of a chord of that circle.

    Multiply the height of the chord times four. For instance, if the height is two, multiply two times four to get eight.

    Square the length of the chord. If the length is four, for example, multiply four times four to get 16.

    Divide your answer from Step 2 by your answer from Step 1. In this example, 16 divided by eight is two.

    Add the height of the chord to your answer from Step 3. For example, two plus two equals four.

    Divide your answer from Step 4 by two to find the radius. Therefore in this instance, four divided by two equals two. The radius in this example is equal to two.

    Things You'll Need

    • Calculator
    • Chord length and height measurements


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Charlotte Johnson is a musician, teacher and writer with a master's degree in education. She has contributed to a variety of websites, specializing in health, education, the arts, home and garden, animals and parenting.

Photo Credits

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