Pls help

39. We can use the Law of Sines, here......we have

D / sin 37 = 17/ sin 28       where D is the distance between towers B and C

Multiply both sides by sin37

D =  17*sin 37 / sin 28 = about 21.8 miles   = answer C

40.  We can use the Law of Cosines  to find θ  

76^2  = 91^2  + 83^2 - 2(91)(83)cosθ       rearrange

[ 76^2 - 91^2 - 83^2] / [ -2 (91)(83)]  = cosθ        take the cosine inverse to find θ

θ   =  arccos  ( [ 76^2 - 91^2 - 83^2] / [ -2 (91)(83)] )  = about   51.55°  = answer A