Question

In this triangle, what is the value of x?

Answer 1

THis is a right triangle so you can use SOH CAH TOA :
Sine = opposite/ hypotenuse
Cosine= adjacent/ hypotenuse
Tangent = opposite/ adjacent
here you have the hypotenuse and are looking to solve for the adjacent side to angle measure 28
so you can set this up like this: cos(28)= x/64
now multiply both sides by 64 and you'll get x = 56.5 just make sure your calculator is in degrees not radians

Answer 2

We're concentrating on "2 sides and the included angle."  
                       adj side         x
cos 28 deg = ------------ = -----------
                          hyp          64 km

Solving for x, we get:     x = (64 km)cos 28 deg

Find cos 28 deg with a calculator and then mult. your result by 64 km.  That will give you "x."