According to the figure we need to evaluate the sin(30°) and the cos(60°). Remember the trigonometric relations defined over the rectangle triangles as follows, suppose we have an angle called "alpha"
[tex]\begin{gathered} \sin(\alpha)=\frac{oc}{h}, \\ \\ cos(\alpha)=\frac{ac}{h}, \\ \\ tan(\alpha)=\frac{co}{ca} \\ \\ where\text{ }h:Hypotenuse,\text{ }ac:Adjacent\text{ }cathetus\text{ and }oc:Opposite\text{ }cathetus \end{gathered}[/tex]
Now, according to the figure, we have that for the angle of 60 degrees:
[tex]\begin{gathered} h=2x,ac=x,oc=\sqrt{3}x \\ \\ \sin(60°)=\frac{oc}{h}=\frac{\sqrt{3}x}{2x}=\frac{\sqrt{3}}{2} \\ \\ \cos(60^{\circ})=\frac{ac}{h}=\frac{x}{2x}=\frac{1}{2} \end{gathered}[/tex]
And for the angle of 30 degrees we get the following
[tex]\begin{gathered} h=2x,oc=x,ac=\sqrt{3}x \\ \\ \sin(30°)=\frac{oc}{h}=\frac{x}{2x}=\frac{1}{2}=\cos(60°) \\ \\ \cos(30^{\circ})=\frac{ac}{h}=\frac{\sqrt{3}x}{2x}=\frac{\sqrt{3}}{2}=\cos(60^{\circ}) \end{gathered}[/tex]
So, your answer is: sin(30°)=1/2=cos(60°).
