Ôn tập chương I
Hướng dẫn Giải Bài 33 (Trang 93, SGK Toán Hình học 9, Tập 1)
<p>Chọn kết quả đ&uacute;ng trong c&aacute;c kết quả dưới đ&acirc;y:</p> <p>a) Trong h&igrave;nh 41, sin<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>&#945;</mi></math> bằng</p> <p>(A)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>5</mn><mn>3</mn></mfrac></math>;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;(B)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>5</mn><mn>4</mn></mfrac></math>;</p> <p>(C)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>3</mn><mn>5</mn></mfrac></math>;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;(D)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>3</mn><mn>4</mn></mfrac></math>.</p> <p>b) Trong h&igrave;nh 42, sinQ bằng</p> <p>(A)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow><mi>P</mi><mi>R</mi></mrow><mrow><mi>R</mi><mi>S</mi></mrow></mfrac></math>;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;(B)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow><mi>P</mi><mi>R</mi></mrow><mrow><mi>Q</mi><mi>R</mi></mrow></mfrac></math>;</p> <p>(C)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow><mi>P</mi><mi>S</mi></mrow><mrow><mi>S</mi><mi>R</mi></mrow></mfrac></math>;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;(D)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow><mi>S</mi><mi>R</mi></mrow><mrow><mi>Q</mi><mi>R</mi></mrow></mfrac></math>.</p> <p>c) Trong h&igrave;nh 43, cos<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>30</mn><mo>&#176;</mo></math> bằng</p> <p>(A)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow><mn>2</mn><mi>a</mi></mrow><msqrt><mn>3</mn></msqrt></mfrac></math>;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;(B)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi>a</mi><msqrt><mn>3</mn></msqrt></mfrac></math>;</p> <p>(C)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><msqrt><mn>3</mn></msqrt><mn>2</mn></mfrac></math>;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;(D)&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><msqrt><mn>3</mn></msqrt><msup><mi>a</mi><mn>2</mn></msup></math>.</p> <p><img class="wscnph" src="https://static.colearn.vn:8413/v1.0/upload/library/16022022/screenshot-152-2IMmro.png" /><img class="wscnph" src="https://static.colearn.vn:8413/v1.0/upload/library/16022022/screenshot-153-U7MCxc.png" /><img class="wscnph" src="https://static.colearn.vn:8413/v1.0/upload/library/16022022/screenshot-154-Eq0sDq.png" /></p> <p><strong>Giải</strong></p> <p>a. C</p> <p>b. D</p> <p>c. C</p> <p>&nbsp;</p>
Xem lời giải bài tập khác cùng bài