Quadrilaterals Notes and Worksheets - Lindsay Bowden - Free Printable

Let’s solve the problem shown in the top-right quadrilateral.

We are given a four-sided shape (a quadrilateral) with three angles labeled:
- 76°
- 104°
- 89°
And one angle labeled as x°.

We know that the sum of all interior angles in any quadrilateral is always 360 degrees.

So, we can add up the known angles and subtract from 360 to find x.

Step 1: Add the known angles.
76 + 104 = 180
180 + 89 = 269

Step 2: Subtract that total from 360.
360 - 269 = 91

So, x = 91

Let’s double-check:
76 + 104 + 89 + 91 = ?
76 + 104 = 180
89 + 91 = 180
180 + 180 = 360 → Correct!

Final Answer:
91