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HMMT 十一月 2012 · 冲刺赛 · 第 4 题

HMMT November 2012 — Guts Round — Problem 4

专题
Discrete Math / 离散数学
难度
L3
来源
HMMT

题目详情

  1. [ 6 ] ABCD is a concave quadrilateral such that ∠ CBA = 50 , ∠ BAD = 80 , ∠ ADC = 30 , and CB = CD . Find ∠ CBD . 2 2
解析
  1. [ 6 ] Answer: 10 ∠ CBD = ∠ CDB because BC = CD . Notice that ∠ BCD = 80 + 50 + 30 = 160, so ∠ CBD = ∠ CDB = 10.