The expression \( \sqrt{1 + \tan^2 c} \) can be simplified using the Pythagorean identity in trigonometry. According to this identity:
\[ 1 + \tan^2 c = \sec^2 c \]
Thus, we can rewrite the square root:
\[ \sqrt{1 + \tan^2 c} = \sqrt{\sec^2 c} \]
Since the square root of a square gives the absolute value, we have:
\[ \sqrt{\sec^2 c} = |\sec c| \]
Therefore, the final result is:
\[ \sqrt{1 + \tan^2 c} = |\sec c| \]