Trig Ratios Right Triangles

I was doing some homework in my math book and I'm having a hard time with these questions. Here is one that i don't have much idea to do with. Grade 11 University math thanks!

Question 1:

The arm of a boom crane is 12m long. Because of the location of the construction site, the angle of inclination of the boom of the crane has a minimum value of 30 degrees and a maximum of 45 degrees. Find the vertical displacement of the end of the boom as

a) an exact value

b) an approximate value, to the nearest tenth of a metre.