Since we have the Hypotenuse given and we need to find the value of the adjacent side of the given angle we would use the Cosine Ratio;
Cos(46) =
To solve for "x" we would first have to isolate the "x" all to itself.
To isolate the variable, simply multiply 13 to the both sides of "="
=> Cos(46) * 13 = x
=> 9.03 = x
So you can write the answer in either of the 2 ways mentioned above, if you need a fully simplified answer the second answer would be a better fit. If u just need the Equation the 1st equation would be the better fit.