Question

Which of the following equations could be used to solve for x in the triangle shown? tan48°=10/x

Answer 1

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