Benchmarks

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总结帝笔记—初三寒假班第三讲

看到“平行”，再看到周长

相似比=周长比

$$\backslash therefore\; AD\; \backslash parallel\; BC\; \backslash therefore\; \backslash triangle\; MAD\; \backslash sim\; \backslash triangle\; MBC$$

$$\backslash therefore\; \backslash text\{相似比为\}\; \backslash frac\{AD\}\{BC\}\; =\; \backslash frac\{8\}\{10\}\; =\; \backslash frac\{4\}\{5\}\; =\; \backslash frac\{MA\}\{MB\}\; =\; \backslash frac\{MD\}\{MC\}$$

$$\backslash therefore\; \backslash frac\{\backslash triangle\; MAD\; \backslash text\{周长\}\}\{\backslash triangle\; MBC\; \backslash text\{周长\}\}\; =\; \backslash frac\{4\}\{5\}\; \backslash quad\; \backslash text\{①\}$$

$$\backslash therefore\; \backslash frac\{MA\}\{MB\}\; =\; \backslash frac\{4\}\{5\}\; \backslash therefore\; \backslash frac\{MA\}\{MA+4\}\; =\; \backslash frac\{4\}\{5\}\; \backslash therefore\; MA\; =\; 16$$

$$\backslash frac\{MD\}\{MC\}\; =\; \backslash frac\{4\}\{5\}\; \backslash therefore\; \backslash frac\{MD\}\{MD+5\}\; =\; \backslash frac\{4\}\{5\}\; \backslash therefore\; MD\; =\; 20$$

$$\backslash therefore\; \backslash triangle\; MAD\; \backslash text\{周长\}\; =\; MA\; +\; AD\; +\; MD\; =\; 16\; +\; 8\; +\; 20\; =\; 44\; \backslash quad\; \backslash text\{②\}$$

$$\backslash therefore\; \backslash text\{由①②可知\}\; \backslash triangle\; MBC\; \backslash text\{周长\}\; =\; 55$$

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