All you have to do in this problem is subtract the bigger length from the smaller length
-8.70833333333 about but you can round to the nearest tenth (-8.7) or nearest whole number (-9)
First you must know that for remarkable angles: cos (0) = 1, cos (π) = - 1, cos (π / 2) = 0, cos (3π / 2) = 0, cos (2π) = 1. Then, by simple substitution in the given formula, you can find the solutions of x. Which for the interval [0, 2π) are: x = π, x = pi divided by two and x = three pi divided by two.Attached solution.
Perimeter is the length around an object