The lengths of two sides of a triangle are shown below: side 1: 3x2 − 2x − 1 side 2: 9x + 2x2 − 3 the perimeter of the triangle is 5x3 + 4x2 − x − 3. part a: what is the total length of the two sides, 1 and 2, of the triangle? (4 points) part b: what is the length of the third side of the triangle? (4 points) part c: do the answers for part a and part b show that the polynomials are closed under addition and subtraction? justify your answer