This Problem Set is a part of the Lesson 1, Unit 7, Grade 8. Use the Pythagorean theorem to estimate the length of the unknown side of the right triangle. Explain why your estimate makes sense. Let be x the length of the unknown side. The number 56 is between the perfect squares 49 and 64. Since it closer to 49 than it is to 64, the length of the unknown side of the triangle is closer to 7 than it is to 8.