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How Do You Find a Missing Angle in a Quadrilateral?

Find the value of x in the diagram below

Summary

  1. n is equal to the number of sides of our polygon
  2. Since n=4, we have a quadrilateral
  3. Add the four angle measurements together and set them equal to 360°
  4. This gives us an equation we can solve for x

Notes

    1. Our polygon has 4 sides, so it is a quadrilateral
    1. To find the sum of the angles in a polygon, subtract 2 from the number of sides and multiply by 180
    1. We can add our four angle measurements together and set them equal to 360°
    2. This will give us an equation we can solve for x
    1. Add the decimals to simplify the left hand side
    2. Subtract 261.2 from both sides to get x by itself
    3. This gives us the measure of our missing angle, 98.8°