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)