Option B: 4.0 cm is the value of w
Explanation:
It is given that
,
,
and 
Using the law of sines, we have,

Substituting the values, we have,

Cross multiplying, we get,

Simplifying, we have,

Dividing both sides by 0.515, we have,

Thus, the value of w is 4.0 cm
Hence, Option B is the correct answer.
Step by step explanation
4n-8=5
4n= 5+8
4n=13
4/4 n = 13/4
n= 13/4
Answer:
This is trigonomentry
Use SOHCAHTOA
where :
s is sin
c is cos
t is tan
o is opposite (side)
h is hypotenuse (opposite of 90 degree angle)
and a is adjacent (side)
Sin = o/h
cos = a/h
tan = o/a
in this case we are looking for side BC which is the hypotenuse(h)
and we have the side adjacent(a) to angle 71
since we have a and h determine what to use SIN, COS, OR TAN?
we should use Cos
they‘ve given the angle so we should do this...
Cos71 =
Cos71 = 
now apply algebra...
6.3/cos71= BC
BC= 19.3507869666
BC = 19.4 (3SF)