Answer:
B
Step-by-step explanation:
Using Pythagoras' identity in the right triangle.
The square on the hypotenuse h is equal to the sum of the squares on the other 2 sides, that is
h² = 3² + 7² = 9 + 49 = 58 ( take the square root of both sides )
h = [tex]\sqrt{58}[/tex] → B
