A 16 inch pendulum swings through an angle of 40 . How far does the tip of the pendulum travel in a singles swing

10.945

Step-by-step explanation:

From the above, we need to find the side "a" because that is how far the pendulum swings at 40. Using cosine rule which the below image states,we will derive the answer 10.945

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.