شاه کلید نکات
شاه کلید سوال
1اگر پاره خط های\(DE\,,\,CD\,,\,BC\,,\,AB\)با هم برابر باشند، تساوی ها را با نوشتن عدد مناسب کامل کنید.
\(\begin{array}{l}\overline {AC} = \cdots \cdots \overline {AB} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\overline {CE} = \cdots \cdots \overline {AE} \\\\\overline {AE} = \cdots \cdots \overline {BE} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\overline {BC} = \cdots \cdots \overline {BC} \end{array}\)
\(\begin{array}{l}\overline {AC} = 2\,\,\overline {AB} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\overline {CE} = \frac{1}{2}\,\,\overline {AE} \\\\\overline {AE} = \frac{4}{3}\,\,\overline {BE} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\overline {BC} = 1\,\,\overline {BC} \end{array}\)
2در شکل مقابل نقاط\(D\,,\,C\,,\,B\,,\,A\)روی یک خط قرار گرفته اند.
می دانیم \(\overline {AB} = \overline {CD} \)
کدام پاره خط هم اندازهٔ AC است؟ .......... چرا؟
\(\begin{array}{l}\overline {AC} = \overline {CE} = \overline {BD} \\\\\overline {AD} = \overline {EB} \end{array}\)
چون
\(\begin{array}{l}\overline {AC} = \overline {AB} + \overline {CB} \\\\\overline {BD} = \overline {BC} + \overline {CD} \end{array}\)
و چون \(\overline {BC} = \overline {CB} \)و \(\overline {AB} = \overline {CD} \)در نتیجه \(\overline {AC} = \overline {BD} \)
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