Acronym to remember the 3 basic trigonomic functions:
Soh - Cah - Toa
opposite
sin = --------------------
hypotenuse
adjacent
cos = -------------------
hypotenuse
opposite
tan = -----------------
adjacent
In your case, you can set up a sine trigonomic function, like this:
Sin 48 = 10 (adjacent)
-----
x (hypotenuse)
10
(x) Sin 48 = ------ (x)
x
(x) Sin 48 = 10
-------------- -------------
Sin 48 Sin 48
Plug in 10(sin)(48) into a calculator.
x = 7.43
I just realized that you didn't ask me to find the answer, but now you will know even more than you need to :D