Use the image to answer the question.

An illustration shows a triangle in which the two opposite sides are of same length, as indicated by congruent cross marks on each side. The angle formed by the convergence of these sides of the same length is 18 degrees. The two angles of the base opposite to the 18 degrees vertex are each labeled as x.

Find the value of x
.

(1 point)
Responses

162°
162 degrees

80°
80 degrees

76°
76 degrees

81°

1 answer

To find the value of \( x \) in the isosceles triangle described, we can use the properties of triangles and the information given.

In an isosceles triangle, the angles opposite to the congruent sides are equal. Given that the angle at the vertex (where the two equal sides meet) is \( 18^\circ \), we can use the fact that the sum of all angles in a triangle is \( 180^\circ \).

Let the two equal angles be represented as \( x \). The equation can be set up as follows:

\[ x + x + 18^\circ = 180^\circ \]

This simplifies to:

\[ 2x + 18^\circ = 180^\circ \]

Subtract \( 18^\circ \) from both sides:

\[ 2x = 180^\circ - 18^\circ \]

\[ 2x = 162^\circ \]

Now, divide both sides by 2:

\[ x = \frac{162^\circ}{2} \]

\[ x = 81^\circ \]

Therefore, the value of \( x \) is \( 81^\circ \).

Final Answer: 81°