We are given a diagram with a triangle and an exterior angle. The triangle has two sides that are marked as equal, so it's an isosceles triangle. We need to find the value of $k$, which represents an angle inside the triangle. An exterior angle of $83^{\circ}$ is also given.
2025/3/25
1. Problem Description
We are given a diagram with a triangle and an exterior angle. The triangle has two sides that are marked as equal, so it's an isosceles triangle. We need to find the value of , which represents an angle inside the triangle. An exterior angle of is also given.
2. Solution Steps
First, let's analyze the isosceles triangle. Since two sides are equal, the angles opposite those sides are also equal. One of these angles is .
The exterior angle and are supplementary, so their sum is . Thus:
However, if the triangle is isosceles, let the other equal angle also be denoted as .
Since the angles in a triangle add up to , we have:
Also note that the exterior angle to angle is degrees.
Therefore,
. Then,
.
So .
.
.
.
This does not make sense.
The angles k and 83 degrees make a straight line, thus they are supplementary and add up to 180 degrees. Therefore,
The isosceles triangle has two equal angles, say .
Thus the angles in the triangle are .
The angles in a triangle sum to
1
8
0. So $k + x + x = 180$
Since the angle and 83 degree form an exterior angle. The remote interior angles are and . Then their sum is 83 degrees, which means degrees.
Thus
Subtract the two equation, we have
Then, , which makes no sense.
The diagram shows k and 83 as supplementary angles.