I'm not even sure how to find h in this problem.

Step-by-step explanation:

See the attached image.  Notice that the two right triangles have the same angles.  Therefore, they are similar.  So we can write a proportion:

h / 12 = 20 / 30

h = 8

The value of h is 8 ft.

hope it you

step-by-step explanation:

sin(7pi/6 - pi/3)  

= sin(7pi/6 - 2pi/6)  

= sin(5pi/6)  

= sin(pi - pi/6)  

= sin(pi/6)  

= 1/2  

sin 7pi/6 - sin pi/3  

= sin (pi + pi/6) - sin pi/3  

= -sin pi/6 - sin pi/3  

= -1/2 - sqrt(3)/2  

= -(1+sqrt(3))2