The Renaissance period was not only a new era of Humanism, but also a revival of Platonism in which mathematics was the key for understanding the universe. This belief was manifested by Kepler's model of the solar system and Vincenzo Galilei's twelve-tone equal temperament.

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?

Brian has an unlimited number of cents (pennies), nickels, and dimes. in how many different ways can he pay 1414cents¢ for a chocolate mint?

Adriveway is 60-feet long by 6-feet wide. the length and width of the driveway will each be increased by the same number of feet. the following expression represents the perimeter of the larger driveway: (x + 60) + (x + 6) + (x + 60) + (x + 6) which expression is equivalent to the expression for the perimeter of the larger driveway? a) 2(x + 66) b) 4x + 33 c) 4(x + 33) d) 4(x + 132)