No, not all right triangles are isosceles. A right triangle is defined as a triangle with one angle measuring 90 degrees. An isosceles triangle is defined as a triangle with at least two sides of equal length.
While it is true that some right triangles can be isosceles (for example, a right triangle with two angles measuring 45 degrees—thus the two legs are of equal length), this is not the case for all right triangles. A right triangle can also have three sides of different lengths, which would make it a scalene triangle.
To summarize, while there can be right isosceles triangles, the broader category of right triangles includes both isosceles and scalene triangles. Therefore, it’s not accurate to say that all right triangles are isosceles.