Describe what happens to the three points of concurrency that determine the Euler line when the triangle is (a) isosceles, (b) equilateral.

To understand what happens to the three points of concurrency that determine the Euler line in different types of triangles, let's first define what the Euler line is. The Euler line is a line that passes through three key points of a triangle: the orthocenter, the centroid, and the circumcenter. Now, let's discuss what happens to these points in different types of triangles:

(a) Isosceles Triangle:
In an isosceles triangle, two sides of the triangle are of equal length. When the triangle is isosceles, the Euler line remains the same. The orthocenter, centroid, and circumcenter all lie on the Euler line, and the positions of these points do not change. The Euler line passes through the orthocenter (the point where the altitudes of the triangle intersect), the centroid (the point where the medians of the triangle intersect), and the circumcenter (the point equidistant from the three vertices of the triangle).

(b) Equilateral Triangle:
In an equilateral triangle, all three sides are of equal length. When the triangle is equilateral, an interesting thing happens. All three points of concurrency that determine the Euler line coincide and become the same point. This means that the orthocenter, centroid, and circumcenter all coincide and become a single point. Therefore, the Euler line, in this case, is actually a point, rather than a line. This point is called the center of the equilateral triangle.

In summary, in an isosceles triangle, the Euler line remains the same, passing through the orthocenter, centroid, and circumcenter. In an equilateral triangle, the Euler line becomes a single point, which is the center of the equilateral triangle.