Use Pythagoras’ Theorem to figure out if it is scalene or right-angled.
20^2 = 400
10^2 = 100
17^2 = 289
400 + 100 doesn’t equal 289
100 + 289 doesn’t equal 400
400+ 289 doesn’t equal 100
So the triangle can’t have a right angle, so therefore is a SCALENE triangle.