Question

Find the value of ( sin 39 /cos 51)

Answer 1

Notice that $39=90-51$ and recall the identity $\sin(90-x)=\cos(x)$

$\frac{\sin(39)}{\cos(51)}=\frac{\sin(90-51)}{\cos(51)}=\frac{\cos(51)}{\cos(51)}=\boxed{~1~}$