PLEASE HELP ME ASAP

Answer:
20.04 units
Step-by-step explanation:
The diagram shows right triangle ABC. Use the definition of the cosine:
[tex]\cos \angle C=\dfrac{\text{Adjacent leg}}{\text{Hypotenuse}}\\ \\\cos \angle C=\dfrac{BC}{AC}\\ \\\cos 51^{\circ}=\dfrac{BC}{27}\\ \\BC=27\cdot \cos 51^{\circ}\\ \\BC\approx 20.04\ units[/tex]