What expression is equivalent to sin 7 pi divided by 6

Plzz ! if you were constructing a triangular frame, and you had wood in the length of 4 inches, 4 inches, and 7 inches, would it make a triangle? would you be able to create a frame from these pieces of wood? yes or no? = explain your mathematical thinking/show your work:

Which expression represents the total perimeter of her sandwich, and if x = 1.2, what is the approximate length of the crust?

Check image and write the letter of the answer