Answer:
Step-by-step explanation:
[tex]sin60=\frac{HR}{72}\\ \\ HR=72sin60\\ \\ \text{They are checking to see if you know the relationships of the 30,60,90 triangle whos sides opposite of those angles are }1,\sqrt{3},2\\ \\ sin60=\frac{\sqrt{3}}{2}\\ \\ HR=\frac{72\sqrt{3}}{2}\\ \\HR=36\sqrt{3}[/tex]
