1. Identify the side lengths:
a = 10, b = 16, c = 20.
2. Apply the Pythagorean theorem to check if the triangle is right-angled:
a^2 + b^2 = c^2.
3. Compute the squares of each side:
10^2 = 100,
16^2 = 256,
20^2 = 400.
4. Add the squares of the two shorter sides:
100 + 256 = 356.
5. Compare this sum to the square of the longest side:
356 \neq 400.
The triangle is not a right-angled triangle.