You have not provided specific dimensions for the tank, but you are referencing what appears to be a Pythagorean-like theorem where a, b, and c represent the sides of a right triangle. However, the exponents on your variables suggest something more complex than the classical Pythagorean theorem. The classical theorem states that for a right triangle with legs of lengths a and b, and hypotenuse of length c:
a^2 + b^2 = c^2
The formula provided in your question is:
a^35 + b^16 = c^12
This equation does not resemble a common geometric theorem. To answer your question with more typical notation, we assume that the tank is a rectangular prism (a 3D rectangle), and the spider is trying to form a diagonal that connects two opposing corners of the tank.
The diagonal of this 3D space forms the hypotenuse of a right-angled triangle, where the three sides are the length, width, and height of the tank. If we label these sides as L (length), W (width), and H (height), the length of the diagonal (D) can be calculated using the 3D version of the Pythagorean theorem:
D = √(L^2 + W^2 + H^2)
For this problem, we need the actual measurements for L, W, and H of the tank. Unfortunately, those have not been provided in your question.
You would calculate D using those provided lengths in their appropriate units (say, inches). After calculating the value using the formula, you would round to the nearest tenth as requested.
Please provide the dimensions of the tank in question, or adjust the formula so that it represents an accurate geometrical relationship, and I can help you calculate the approximate length of the spider's thread.