Given that the garden is rectangular and a line of roses form the diagonal 18.4 m long, we required to calculate the length of the perpendicular side.
Here we shall use the Pythagorean theorem.
c²=a²+b²
where c is the hypotenuse, a and b are the legs.
from the information given:
c=18.4 m
a=13 m
plugging this into our expression we get:
18.4²=13²+b²
next we solve for the value of b
b²=18.4²-13²
b²=338.56-169
b²=169.56
b=√169.56
b=13.0215
hence the length to the nearest tenth of a meter will be approximately 13.0 m