\(S=\dfrac{1}{2}\cdot5\cdot10\cdot sin45=\dfrac{25\sqrt{2}}{2}\)
\(cosC=\dfrac{5^2+10^2-AC^2}{2\cdot5\cdot10}\)
=>\(125-AC^2=50\sqrt{2}\)
=>AC=7,37cm
BC/sinA=CA/sinB=AB/sinC=2R
=>10/sinA=7,37/sin45=5/sinC=2R
=>A=74 độ; gócC=61 độ; R=5,21(cm)
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