tam giác vuông

T

toiyeu9a3

Ta có: $h_a.a = h_b.b = h_c.c = 2S = x$
\Rightarrow $a^2 = (\dfrac{x}{h_a})^2 = \dfrac{x^2}{25}$
Tương tự:
$b^2 = \dfrac{x^2}{20}$
$c^2 = \dfrac{x^2}{100}$
\Rightarrow $b^2 = a^2 + c^2$
\Rightarrow $\triangle ABC$ vuông
 
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