三角形外接圆周长代码,C代码库,德仔网

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【C】三角形外接圆周长
作者:Dezai.CN / 发布于2011/7/8/ 701
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<div><span style="color: #0000ff">#define</span><span style="color: #000000"> PAI 3.1415926</span><span style="color: #000000">

#include </span><span style="color: #000000"><</span><span style="color: #000000">stdio.h</span><span style="color: #000000">></span><span style="color: #000000">
#include </span><span style="color: #000000"><</span><span style="color: #000000">math.h</span><span style="color: #000000">></span><span style="color: #000000">
</span><span style="color: #008000">//</span><span style="color: #008000">求三角形外接圆周长

</span><span style="color: #008000">//</span><span style="color: #008000">三角形三边a,b,c,半周长p（p=(a+b+c)/2） 
</span><span style="color: #008000">//</span><span style="color: #008000">面积：S= &radic;[p(p - a)(p - b)(p - c)]
</span><span style="color: #008000">//</span><span style="color: #008000">外接圆半径 R=abc/4S 
</span><span style="color: #008000">//</span><span style="color: #008000">外接圆半径 R=abc/4&radic;[p(p - a)(p - b)(p - c)] 
</span><span style="color: #008000">//</span><span style="color: #008000">外接圆周长C=2*PAI*R</span><span style="color: #008000">
</span><span style="color: #000000">
</span><span style="color: #0000ff">float</span><span style="color: #000000"> S(</span><span style="color: #0000ff">float</span><span style="color: #000000"> x1,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y1,</span><span style="color: #0000ff">float</span><span style="color: #000000"> x2,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y2,</span><span style="color: #0000ff">float</span><span style="color: #000000"> x3,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y3){
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> ((x1</span><span style="color: #000000">-</span><span style="color: #000000">x3)</span><span style="color: #000000">*</span><span style="color: #000000">(y2</span><span style="color: #000000">-</span><span style="color: #000000">y3) </span><span style="color: #000000">-</span><span style="color: #000000"> (y1</span><span style="color: #000000">-</span><span style="color: #000000">y3)</span><span style="color: #000000">*</span><span style="color: #000000">(x2</span><span style="color: #000000">-</span><span style="color: #000000">x3) );
}

</span><span style="color: #0000ff">float</span><span style="color: #000000"> cal_center_x(</span><span style="color: #0000ff">float</span><span style="color: #000000"> x1,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y1,</span><span style="color: #0000ff">float</span><span style="color: #000000"> x2,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y2,</span><span style="color: #0000ff">float</span><span style="color: #000000"> x3,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y3){
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> (S(x1</span><span style="color: #000000">*</span><span style="color: #000000">x1</span><span style="color: #000000">+</span><span style="color: #000000">y1</span><span style="color: #000000">*</span><span style="color: #000000">y1,y1, x2</span><span style="color: #000000">*</span><span style="color: #000000">x2</span><span style="color: #000000">+</span><span style="color: #000000">y2</span><span style="color: #000000">*</span><span style="color: #000000">y2, y2,x3</span><span style="color: #000000">*</span><span style="color: #000000">x3</span><span style="color: #000000">+</span><span style="color: #000000">y3</span><span style="color: #000000">*</span><span style="color: #000000">y3,y3)</span><span style="color: #000000">/</span><span style="color: #000000">(</span><span style="color: #800080">2</span><span style="color: #000000">*</span><span style="color: #000000">S(x1,y1,x2,y2,x3,y3)) );
}

</span><span style="color: #0000ff">float</span><span style="color: #000000"> cal_center_y(</span><span style="color: #0000ff">float</span><span style="color: #000000"> x1,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y1,</span><span style="color: #0000ff">float</span><span style="color: #000000"> x2,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y2,</span><span style="color: #0000ff">float</span><span style="color: #000000"> x3,</span><span style="color: #0000ff">float</span><span style="color: #000000"> y3){
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> (S(x1, x1</span><span style="color: #000000">*</span><span style="color: #000000">x1</span><span style="color: #000000">+</span><span style="color: #000000">y1</span><span style="color: #000000">*</span><span style="color: #000000">y1, x2, x2</span><span style="color: #000000">*</span><span style="color: #000000">x2</span><span style="color: #000000">+</span><span style="color: #000000">y2</span><span style="color: #000000">*</span><span style="color: #000000">y2, x3, x3</span><span style="color: #000000">*</span><span style="color: #000000">x3</span><span style="color: #000000">+</span><span style="color: #000000">y3</span><span style="color: #000000">*</span><span style="color: #000000">y3) </span><span style="color: #000000">/</span><span style="color: #000000"> (</span><span style="color: #800080">2</span><span style="color: #000000">*</span><span style="color: #000000">S(x1,y1,x2,y2,x3,y3)));
}

</span><span style="color: #0000ff">int</span><span style="color: #000000"> main()
{
 </span><span style="color: #0000ff">float</span><span style="color: #000000"> x1, y1, x2, y2, x3, y3, x, y;
 </span><span style="color: #0000ff">while</span><span style="color: #000000">(scanf(</span><span style="color: #800000">"</span><span style="color: #800000">%f %f %f %f %f %f</span><span style="color: #800000">"</span><span style="color: #000000">, </span><span style="color: #000000">&</span><span style="color: #000000">x1, </span><span style="color: #000000">&</span><span style="color: #000000">y1, </span><span style="color: #000000">&</span><span style="color: #000000">x2, </span><span style="color: #000000">&</span><span style="color: #000000">y2, </span><span style="color: #000000">&</span><span style="color: #000000">x3, </span><span style="color: #000000">&</span><span style="color: #000000">y3) </span><span style="color: #000000">!=</span><span style="color: #000000"> EOF)
 {
 x </span><span style="color: #000000">=</span><span style="color: #000000"> cal_center_x(x1, y1, x2, y2, x3, y3);
 y </span><span style="color: #000000">=</span><span style="color: #000000"> cal_center_y(x1, y1, x2, y2, x3, y3);
 </span><span style="color: #0000ff">float</span><span style="color: #000000"> C </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #800080">2</span><span style="color: #000000">*</span><span style="color: #000000">PAI</span><span style="color: #000000">*</span><span style="color: #000000">sqrt((x</span><span style="color: #000000">-</span><span style="color: #000000">x1)</span><span style="color: #000000">*</span><span style="color: #000000">(x</span><span style="color: #000000">-</span><span style="color: #000000">x1)</span><span style="color: #000000">+</span><span style="color: #000000">(y</span><span style="color: #000000">-</span><span style="color: #000000">y1)</span><span style="color: #000000">*</span><span style="color: #000000">(y</span><span style="color: #000000">-</span><span style="color: #000000">y1));
 printf(</span><span style="color: #800000">"</span><span style="color: #800000">%.2f\n</span><span style="color: #800000">"</span><span style="color: #000000">, C);
 } 
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> </span><span style="color: #800080">0</span><span style="color: #000000">;
}</span></div>
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