If a triangle has sides 5, 12, and 13, is it a right triangle? A Yes B No C Not enough information D Only if it is isosceles ✓ Correct Answer: Option A 5² + 12² = 25 + 144 = 169 = 13². Since a² + b² = c², it is a right triangle. Practice ACT Exam Prep Quizzes → Browse All Questions Study Flashcards