Find the exact length of the missing sides

For finding x:
We want to use tangent because tangent is opposite/adjacent
tan (30)= x/15
Multiply both sides of the equation by 15 to isolate x
Now we have, (15)(tan 30) = x
Simply plug the above equation into your calculator and you should get x=8.66

For y:
We know the angle opposite side y is= 90˚ (it is marked as a right angle)
We are going to use cosine because cosine is adjacent/hypotenuse
So, cos(90)= 15/y
Multiply by y
(y)(cos 90)=15
Now use simple algebra
cos (90) = 0
Y x 0 =15
y=15

Hope this helps. By the way, I am a little rusty on this topic so I am not 100% sure that this is right (I'm 98% sure).