Answer:
x = 16.6
Explanation:
Since we know the measure of an acute angle (31 degrees) of a right angle triangle, and of the side opposite to the angle (10), and we need to find the measure of the adjacent side "x", we use the tangent function:
![tan(\theta) = (opposite)/(adjacent) \\tan(31^o)=(10)/(x)\\x=(10)/(tan(31^o)) \\x \approx 16.64279](https://img.qammunity.org/2021/formulas/mathematics/college/xk30zskh3nnu84e1m9igkedze0qzycd8he.png)
which rounded to one decimal is
x = 16.6