Final answer:
The question appears to involve solving for x, which may require using the quadratic formula in the context of trigonometry or algebraic equations.
Step-by-step explanation:
Based on the information provided, it seems like the question involves finding the value of x using a mathematical method, possibly involving a quadratic equation. The references to quadratic formula, angles, and cosines suggest that this might be related to trigonometry or algebraic equations. However, without a clear equation or context, it's not possible to provide an accurate solution. We can infer that the student might be trying to solve a quadratic equation, which can usually be done using the quadratic formula: x = (-b ± √(b^2 - 4ac))/(2a), where a, b, and c are coefficients of the quadratic equation ax^2 + bx + c = 0.