Answer:
a and b are the legs, and c is the hypotenuse
Explanation:
The legs of a right triangle are always the sides that form the right angle. Looking at the picture, we see that at one corner of the triangle, there's a little square. Remember that this little square always denotes an angle with degree 90, which means this is the right angle. Then, since sides a and b form this angle, we know that a and b are the legs.
Another thing to remember is that the hypotenuse of a right triangle is the side that lies opposite to the right angle. Here, you can see that side c lies opposite to the right angle, so we know it's the hypotenuse.
Hope this helps!