Answer:
21) Yes; 23) Yes
Step-by-step explanation:
If the lengths form a right triangle, the sum of the squares of the two shorter sides should equal the square of the longest side (Pythagoras).
21)
5² + 12² = 13²
25 + 144 = 169
169 = 169
The lengths form a right triangle.
23)
3² + 4² = 5²
9 + 16 = 25
25 = 25
The lengths form a right triangle.
