Bài 6: Cung chứa góc
Hướng dẫn giải Bài 44 (Trang 86 SGK Toán 9 Hình học, Tập 2)
<p>Cho tam gi&aacute;c ABC vu&ocirc;ng&nbsp; tại A ,c&oacute; cạnh BC cố định . Gọi I l&agrave; giao điểm của ba đường ph&acirc;n gi&aacute;c trong.T&igrave;m quỹ t&iacute;ch điểm I khi A thay đổi.</p> <p>Giải</p> <p><img class="wscnph" src="https://static.colearn.vn:8413/v1.0/upload/library/28022022/z3219473007491_4ec9257f21016e6314c35796c6c96d43-z5ax6z.jpg" /></p> <p>Theo t&iacute;nh chất g&oacute;c ngo&agrave;i của tam gi&aacute;c,ta c&oacute;:</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><mover><msub><mi>I</mi><mn>1</mn></msub><mo>^</mo></mover><mo>&#160;</mo><mo>=</mo><mover><msub><mi>A</mi><mn>2</mn></msub><mo>^</mo></mover><mo>+</mo><mover><msub><mi>B</mi><mn>1</mn></msub><mo>^</mo></mover><mo>&#160;</mo><mfenced><mn>1</mn></mfenced><mspace linebreak="newline"/><mover><msub><mi>I</mi><mn>2</mn></msub><mo>^</mo></mover><mo>=</mo><mover><msub><mi>A</mi><mn>2</mn></msub><mo>^</mo></mover><mo>+</mo><mover><msub><mi>B</mi><mn>2</mn></msub><mo>^</mo></mover><mo>&#160;</mo><mo>&#160;</mo><mfenced><mn>2</mn></mfenced><mspace linebreak="newline"/><mi>C</mi><mi>&#7897;</mi><mi>n</mi><mi>g</mi><mo>&#160;</mo><mfenced><mn>1</mn></mfenced><mo>&#160;</mo><mi>v</mi><mi>&#224;</mi><mo>&#160;</mo><mfenced><mn>2</mn></mfenced><mo>&#160;</mo><mi>v</mi><mi>&#7871;</mi><mo>&#160;</mo><mi>v</mi><mi>&#7899;</mi><mi>i</mi><mo>&#160;</mo><mi>v</mi><mi>&#7871;</mi><mo>&#160;</mo><mi>t</mi><mi>a</mi><mo>&#160;</mo><mi>&#273;</mi><mi>&#432;</mi><mi>&#7907;</mi><mi>c</mi><mo>&#160;</mo><mspace linebreak="newline"/><mover><msub><mi>I</mi><mn>1</mn></msub><mo>^</mo></mover><mo>+</mo><mover><msub><mi>I</mi><mn>2</mn></msub><mo>^</mo></mover><mo>&#160;</mo><mo>=</mo><mover><msub><mi>A</mi><mn>1</mn></msub><mo>^</mo></mover><mo>&#160;</mo><mo>+</mo><mover><msub><mi>A</mi><mn>2</mn></msub><mo>^</mo></mover><mo>&#160;</mo><mo>+</mo><mover><msub><mi>B</mi><mn>1</mn></msub><mo>^</mo></mover><mo>&#160;</mo><mo>+</mo><mover><msub><mi>B</mi><mn>2</mn></msub><mo>^</mo></mover><mspace linebreak="newline"/><mi>H</mi><mi>a</mi><mi>y</mi><mo>&#160;</mo><mover><mi>I</mi><mo>^</mo></mover><mo>=</mo><mn>90</mn><mo>&#176;</mo><mo>+</mo><mn>45</mn><mo>=</mo><mn>135</mn><mo>&#176;</mo><mspace linebreak="newline"/><mi>&#272;</mi><mi>i</mi><mi>&#7875;</mi><mi>m</mi><mo>&#160;</mo><mi>I</mi><mo>&#160;</mo><mi>n</mi><mi>h</mi><mi>&#236;</mi><mi>n</mi><mo>&#160;</mo><mi>&#273;</mi><mi>o</mi><mi>&#7841;</mi><mi>n</mi><mo>&#160;</mo><mi>t</mi><mi>h</mi><mi>&#7859;</mi><mi>n</mi><mi>g</mi><mo>&#160;</mo><mi>B</mi><mi>C</mi><mo>&#160;</mo><mi>c</mi><mi>&#7889;</mi><mo>&#160;</mo><mi>&#273;</mi><mi>&#7883;</mi><mi>n</mi><mi>h</mi><mo>&#160;</mo><mi>d</mi><mi>&#432;</mi><mi>&#7899;</mi><mi>i</mi><mo>&#160;</mo><mi>g</mi><mi>&#243;</mi><mi>c</mi><mo>&#160;</mo><mn>135</mn><mo>&#176;</mo><mo>&#160;</mo><mi>k</mi><mi>h</mi><mi>&#244;</mi><mi>n</mi><mi>g</mi><mo>&#160;</mo><mi>&#273;</mi><mi>&#7893;</mi><mi>i</mi><mo>&#160;</mo><mo>,</mo><mi>v</mi><mi>&#7853;</mi><mi>y</mi><mo>&#160;</mo><mi>q</mi><mi>u</mi><mi>&#7929;</mi><mo>&#160;</mo><mi>t</mi><mi>&#237;</mi><mi>c</mi><mi>h</mi><mo>&#160;</mo><mi>c</mi><mi>&#7911;</mi><mi>a</mi><mo>&#160;</mo><mi>I</mi><mo>&#160;</mo><mi>l</mi><mi>&#224;</mi><mo>&#160;</mo><mi>c</mi><mi>u</mi><mi>n</mi><mi>g</mi><mo>&#160;</mo><mspace linebreak="newline"/><mi>c</mi><mi>h</mi><mi>&#7913;</mi><mi>a</mi><mo>&#160;</mo><mi>g</mi><mi>&#243;</mi><mi>c</mi><mo>&#160;</mo><mn>135</mn><mo>&#176;</mo><mo>&#160;</mo><mi>d</mi><mi>&#7921;</mi><mi>n</mi><mi>g</mi><mo>&#160;</mo><mi>t</mi><mi>r</mi><mi>&#234;</mi><mi>n</mi><mo>&#160;</mo><mi>&#273;</mi><mi>o</mi><mi>&#7841;</mi><mi>n</mi><mo>&#160;</mo><mi>t</mi><mi>h</mi><mi>&#7859;</mi><mi>n</mi><mi>g</mi><mo>&#160;</mo><mi>B</mi><mi>C</mi><mo>&#160;</mo><mo>(</mo><mi>m</mi><mi>&#7897;</mi><mi>t</mi><mo>&#160;</mo><mi>c</mi><mi>u</mi><mi>n</mi><mi>g</mi><mo>)</mo><mo>.</mo><mo>&#160;</mo></math>&nbsp;</p>
Hướng dẫn Giải Bài 44 (Trang 86, SGK Toán Hình học 9, Tập 2)
GV: GV colearn
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Hướng dẫn Giải Bài 44 (Trang 86, SGK Toán Hình học 9, Tập 2)
GV: GV colearn