Two sides of a triangle are 5cm and 7cm what is the third side

Abaker has 5 1/4 pies in her shop. she cut the pies in pieces that are each 1/8 of a whole pie. how many pieces of pie does she have?

Here is their argument. given the obtuse angle x, we make a quadrilateral abcd with ∠dab = x, and ∠abc = 90◦, and ad = bc. say the perpendicular bisector to dc meets the perpendicular bisector to ab at p. then pa = pb and pc = pd. so the triangles pad and pbc have equal sides and are congruent. thus ∠pad = ∠pbc. but pab is isosceles, hence ∠pab = ∠pba. subtracting, gives x = ∠pad−∠pab = ∠pbc −∠pba = 90◦. this is a preposterous conclusion – just where is the mistake in the "proof" and why does the argument break down there?

Question 10 of 211 pointuse the elimination method to solve the system of equations. choose thecorrect ordered pair.10x +2y = 643x - 4y = -36a. (4,12)b. (-3, 11)c. (2,10)d. (-5, 8)