Math Problem Statement

Calculate the size of the angle marked x in the pentagon shown below.

Solution

To solve for the angle xx in this pentagon, we can use the fact that the sum of the interior angles of a polygon with nn sides is given by:

Sum of interior angles=(n2)×180\text{Sum of interior angles} = (n - 2) \times 180^\circ

Since this is a pentagon (n=5n = 5), we calculate the sum of its interior angles as:

(52)×180=3×180=540(5 - 2) \times 180^\circ = 3 \times 180^\circ = 540^\circ

Now, we add up the known angles and set up an equation to solve for xx.

The known angles are:

  • 5757^\circ
  • 2727^\circ
  • 131131^\circ
  • 6161^\circ

Adding these:

57+27+131+61=27657^\circ + 27^\circ + 131^\circ + 61^\circ = 276^\circ

Since the sum of all interior angles is 540540^\circ, we can find xx by subtracting the sum of the known angles from 540540^\circ:

x=540276=264x = 540^\circ - 276^\circ = 264^\circ

Therefore, the value of xx is 264264^\circ.

If you have further questions or need clarification, feel free to ask!


Related Questions to Explore Further:

  1. How do you find the sum of interior angles for any polygon?
  2. Why does a pentagon have a total of 540540^\circ in its interior angles?
  3. What would be the sum of the exterior angles of any polygon, and why?
  4. How can you verify the calculation for the angle xx using exterior angles?
  5. How would the approach change if it were a regular pentagon (all angles and sides equal)?

Tip:

For any polygon, the sum of the exterior angles is always 360360^\circ, regardless of the number of sides. This is a useful property when solving problems involving polygons.

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Math Problem Analysis

Mathematical Concepts

Polygon Interior Angles
Angle Sum in Polygons
Pentagon Geometry

Formulas

Sum of interior angles of a polygon = (n - 2) × 180°
x = Total Interior Angle Sum - Sum of Known Angles

Theorems

Polygon Interior Angle Sum Theorem

Suitable Grade Level

Grades 8-10