Final answer:
The triangle with angles measuring 63°, 30°, and 87° is not an isosceles triangle because all three angles are different. Isosceles triangles have at least two angles that are equal.
Step-by-step explanation:
The question is asking about the properties of a triangle and whether it can be classified as an isosceles triangle given the measurements of its angles.
To classify a triangle as isosceles, we should have at least two angles that are identical. Since the provided angles are 63°, 30°, and 87°, we can easily see that these angles are all different.
This indicates that the triangle is not an isosceles triangle. It is crucial to remember the basic property of a triangle, which is that it is a three-sided figure lying on a plane with three angles adding up to 180 degrees. As the sum of the given angles equals 180°, it confirms that we are indeed looking at a valid triangle, just not an isosceles one.