MathDB
Pythagorean or Similar Triag

Source: 2021 AMC 10B #15

November 17, 2021
AMCAMC 10AMC 10 B

Problem Statement

In square ABCDABCD, points PP and QQ lie on AD\overline{AD} and AB\overline{AB}, respectively. Segments BP\overline{BP} and CQ\overline{CQ} intersect at right angles at RR, with BR=6BR=6 and PR=7PR=7. What is the area of the square?
[asy] size(170); defaultpen(linewidth(0.6)); real r = 3.5; pair A = origin, B = (5,0), C = (5,5), D = (0,5), P = (0,r), Q = (5-r,0), R = intersectionpoint(B--P,C--Q); draw(A--B--C--D--A^^B--P^^C--Q^^rightanglemark(P,R,C,7)); dot("AA",A,S); dot("BB",B,S); dot("CC",C,N); dot("DD",D,N); dot("QQ",Q,S); dot("PP",P,W); dot("RR",R,1.3*S); label("77",(P+R)/2,NE); label("66",(R+B)/2,NE); [/asy] <spanclass=latexbold>(A)</span>85<spanclass=latexbold>(B)</span>93<spanclass=latexbold>(C)</span>100<spanclass=latexbold>(D)</span>117<spanclass=latexbold>(E)</span>125<span class='latex-bold'>(A) </span>85\qquad<span class='latex-bold'>(B) </span>93\qquad<span class='latex-bold'>(C) </span>100\qquad<span class='latex-bold'>(D) </span>117\qquad<span class='latex-bold'>(E) </span>125