hello
to solve this question, we should simply use trigonometric ratios SOHCAHTOA to determine which of the ratios to use

the diagram above is a representation of what we should reference to in terms of position of the sides in a triangle.
to find the length of BC, we have to use sine angle because we have the value of theta and hypothenus and we are solving for opposite

from the calculation above, the length of line BC is equal to 11.80 units