Answer:
B
Explanation:
ABD (half of the rectangle) is a right-angled triangle.
so, Pythagoras applies.
c² = a² + b²
c is the Hypotenuse (the baseline opposite of the 90 degree angle) and in our case the line BD.
a and b are the 2 sides enclosing the 90 degree angle. in our case here the lines AD and AB.
so,
BD² = AD² + AB² = (6-1)² + (5-2)² = 5² + 3² = 25 + 9 = 34
BD = sqrt(34)