For the a triangle to be a right angle triangle, the length of the three sides must form a pythagorean triple. This means that if we apply pythagoras theorem, the square of the length of the longest side must equal the sum of the squares of the length of the other sides. This means that
11^2 must be equal to 4^2 + 7^2
11^ = 121
4^2 + 7^2 = 16 + 49 = 65
Since they are not equal, then the triangle with the given sides, 4, 7, 11 cannot form a right angle triangle.