在极坐标系（p,o）中，直线o=Л÷4（p∈R） p=2sino截得的弦的长是
\u5728\u6781\u5750\u6807\u7cfb\u4e2d\uff0c\u76f4\u7ebfpsin(\u03b8+\u03c0/4)=2\u88ab\u5706p=4\u622a\u5f97\u7684\u5f26\u957f\u4e3a\uff1fPSIN(\u03b8+\u03c0/4)=P(SIN\u03b8*COS\u03c0/4+COS\u03b8*SIN\u03c0/4)=\u221a2/2*PSIN\u03b8+\u221a2/2*PCOS\u03b8
=\u221a2/2(X+Y)=2
=> X+Y=2\u221a2 =>X+Y-2\u221a2=0
P=4 => P²=16 => X²+Y²=16 \u5706\u5fc3(0,0),\u534a\u5f84R=4.
\u5706\u5fc3\u5230\u76f4\u7ebf\u8ddd\u79bb:D=|-2\u221a2|/\u221a(1+1)=2
\u8bbe\u5f26\u957f\u4e3aL,\u6839\u636e\u5782\u5f84\u5b9a\u7406:(L/2)²=R²-D²=4²-2²=16-4=12
=>L=4\u221a3
\u56e0\u6b64,\u7b54\u6848\u4e3a4\u221a3
\u5c06\u6781\u5750\u6807\u8f6c\u5316\u4e3a\u5e73\u9762\u76f4\u89d2\u5750\u6807
\u76f4\u7ebf\u03b8=\u03c0/4(\u03c1\u2208R)\u7b49\u4ef7\u4e8ey=x
P=2sin\u03b8\u7b49\u4ef7\u4e8ey²=x²/3
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