The sum of the measures of the interior angles of a polygon is (n-2)180, where n represents the number of sides.
28^(∘), 130^(∘)
Practice makes perfect
We are given the following figure.
We want to find the measures of the two missing angles using properties of quadrilaterals and parallel lines. Let's start by marking these two angles.
First, we will find the measure of the x^(∘) angle using properties of parallel lines. Note that the given figure is a trapezoid because it has two bases that are parallel. Let's lengthen the bases and the right leg of this trapezoid.
Now we can see a line that intersects two parallel lines. When two parallel lines are cut by a transversal, special angle relationships exist. If we know the measure of one of the angles, we can find the measures of all of the angles. This means that we can use the 152^(∘) angle to find the measure of the x^(∘) angle. Let's start by marking an extra angle in the diagram.
To find the the measure of ∠1, we can analyze the relationship between the 152^(∘) angle and ∠ 1.
Notice that the 152^(∘) angle and ∠ 1 are the interior angles that lie on opposite sides of the transversal. This means that these angles are alternate interior angles. Since the two horizontal lines are parallel, the measures of these angles are equal.
m∠ 1 = 152^(∘)
Now let's take a closer look at ∠ 1 and the x^(∘) angle.
We can see that ∠ 1 and the x^(∘) angle form a straight line. Therefore, these angles are supplementary and the sum of their measures is 180^(∘).
m∠ 1 + x^(∘) = 180^(∘)
Knowing that m∠ 1=152^(∘), we will find the measure of the x^(∘) angle.
Now we will find the value of y using properties of quadrilaterals. Let's start by recalling the rule for the sum of the measures of the interior angles of a polygon.
We got that the sum of the interior angles of the trapezoid is 360^(∘). We can write an equation that represents this situation.
50^(∘) + 152^(∘) + 28^(∘) + y^(∘) = 360^(∘)
Now we can solve this equation for y. For simplicity, we will not write the degree symbol.
