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HMMT 十一月 2012 · 冲刺赛 · 第 3 题

HMMT November 2012 — Guts Round — Problem 3

专题
Contest Math / 竞赛数学
难度
L3
来源
HMMT

题目详情

  1. [ 5 ] Find the area of the region between two concentric circles that have radii 100 and 99.
    HMMT NOVEMBER 2012, 10 NOVEMBER 2012 — GUTS ROUND
    ° ° °

英文原题

[ 5 ] Find the area of the region between two concentric circles that have radii 100 and 99.
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HMMT NOVEMBER 2012, 10 NOVEMBER 2012 — GUTS ROUND

解析

英文解析

  1. [ 5 ]
    2 2
    Answer: 199 π The area of a circle of radius 100 is 100 π , and the area of a circle of radius 99 is 99 π .
    2 2
    Therefore, the area of the region between them is (100 − 99 ) π = (100 + 99)(100 − 99) π = 199 π .