Question

In isosceles triangle RST below, what is the value of y?

Triangle R S T. Angle T is 38 degrees and angles R and S are y.
38 degrees
71 degrees
122 degrees
142 degrees

Answers

GPT-4o mini
In an isosceles triangle, the two angles that are equal are typically the base angles. In triangle RST, angles R and S are equal and both are denoted as \( y \). Angle T is given as \( 38^\circ \).

The sum of the angles in any triangle is always \( 180^\circ \). Therefore, we can set up the equation:

\[
y + y + 38^\circ = 180^\circ
\]

This simplifies to:

\[
2y + 38^\circ = 180^\circ
\]

Next, subtract \( 38^\circ \) from both sides:

\[
2y = 180^\circ - 38^\circ
\]

\[
2y = 142^\circ
\]

Now, divide both sides by 2:

\[
y = \frac{142^\circ}{2} = 71^\circ
\]

Thus, the value of \( y \) is \( 71^\circ \).

The correct answer is \( 71^\circ \).