Answer: D. 1.2 m
Step-by-step explanation:
According to the description, the boy, the side of the tent and the ground form a right triangle, which means we can solve this problem with a trigonometric function.
If in this right triangle the boy (whose length is
) and the ground are the sides of the triangle and the fabric that makes a
angle with ground is the hypotenuse, we can use the function sine:


Isolating the
:

Finally:
This is the length of the fabric