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Fall 2021 AMC 10 B #0khp

Fall 2021 AMC 10 BHard

From module Angle Chasing Mastery

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Understand the scale
Scale 0.5: Easiest math competition problems, often solvable even for early middle school students without experience. 1: Problems strictly for beginners, often at a moderate middle school level. 1.5: Problems for stronger beginner students, on the level of the middling problems in most middle school contests. 2: For motivated beginners, harder questions from the previous categories. 2.5: More advanced beginner problems, hardest questions from previous categories. 3: Early intermediate problems that require more creative thinking. 3.5: Tougher early intermediate problems that consistently stretch into higher-level creative thinking or conceptual knowledge. 4: Intermediate-level problems. 4.5: Upper intermediate problems approaching the upper bound for non-invitational sprint math competitions. 5: More difficult AIME problems or simple proof-based Olympiad-style problems. 6: High-level AIME-styled questions or introductory Olympiad-level questions. 7: Tougher Olympiad-level questions, may require more technical knowledge. 8: High-level Olympiad-level questions. 9: Expert Olympiad-level questions. 9.5: The hardest problems appearing on Olympiads which the strongest students could reasonably solve. 10: Historically notorious problems, generally unsuitable for even very hard competitions because they are exceedingly tedious, long, and difficult.
TrianglesQuadrilateralsAngle chasing

Problem

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?

figure

(A) 85 (B) 93 (C) 100 (D) 117 (E) 125

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