MathDB

Problems(2)

Square Paper Folding

Source: AIME 2008I Problem 15

3/23/2008
A square piece of paper has sides of length 100 100. From each corner a wedge is cut in the following manner: at each corner, the two cuts for the wedge each start at distance 17 \sqrt {17} from the corner, and they meet on the diagonal at an angle of 60 60^\circ (see the figure below). The paper is then folded up along the lines joining the vertices of adjacent cuts. When the two edges of a cut meet, they are taped together. The result is a paper tray whose sides are not at right angles to the base. The height of the tray, that is, the perpendicular distance between the plane of the base and the plane formed by the upper edges, can be written in the form mn \sqrt [n]{m}, where m m and n n are positive integers, m<1000 m < 1000, and m m is not divisible by the n nth power of any prime. Find m \plus{} n. [asy]import math; unitsize(5mm); defaultpen(fontsize(9pt)+Helvetica()+linewidth(0.7));
pair O=(0,0); pair A=(0,sqrt(17)); pair B=(sqrt(17),0); pair C=shift(sqrt(17),0)*(sqrt(34)*dir(75)); pair D=(xpart(C),8); pair E=(8,ypart(C));
draw(O--(0,8)); draw(O--(8,0)); draw(O--C); draw(A--C--B); draw(D--C--E);
label("17\sqrt{17}",(0,2),W); label("17\sqrt{17}",(2,0),S); label("cut",midpoint(A--C),NNW); label("cut",midpoint(B--C),ESE); label("fold",midpoint(C--D),W); label("fold",midpoint(C--E),S); label("3030^\circ",shift(-0.6,-0.6)*C,WSW); label("3030^\circ",shift(-1.2,-1.2)*C,SSE);[/asy]
trigonometrygeometry3D geometrypyramidanalytic geometryvectorAsymptote
Conditions for Integer

Source: AIME 2008II Problem 15

4/3/2008
Find the largest integer n n satisfying the following conditions: (i) n2 n^2 can be expressed as the difference of two consecutive cubes; (ii) 2n\plus{}79 is a perfect square.
modular arithmeticAMCAIMEnumber theoryIntermediate Number TheoryAIME II