Re: [計量] pp1-ps-72
設X與(40-X)兩段
X為circle,r為半徑
(40-X) 為square,(40-X)/4為邊長
周長of circle = 2πr = X -----【1】
Area of circle + Area of square
=πr^2 + [(40-X)/4]^2
【1】代入
=πr^2 + [(40-2πr )/4]^2
=πr^2 + [(10-1/2πr )/4]^2
Ans(E)
(以上內容由美加助教提供)
※ 引述《wonderfulhwh (leeward)》之銘言:
: A thin piece of wire 40 meters long is cut into two pieces. One piece is
: used to form a circle with radius r, and the other is used to form a square.
: No wire is left over. Which of the following represents the total area, in
: square meters, of the circular and the square regions in terms of r ?
: (A) πr^2
: (B) πr^2 + 10
: (C) πr^2+ 1/4π^2r^2
: (D) πr^2 + (40 - 2πr)^2
: (E) πr^2 + (10 – 1/2πr)^2
: 請問為什麼答案是(E)?
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