Question

Треугольник 9 класс, тема "Решение треугольников"

Answer 1

$AC=AH+CH\AH^2+BH^2=AB^2\CH^2+BH^2=BC^2\AC^2=AB^2+BC^2\AC^2=AH^2+BH^2+CH^2+BH^2\AC^2=(AH+CH)^2\(AH+CH)^2=AH^2+2BH^2+CH^2\2AHcdot CH=2BH^2\AHcdot CH=BH^2\CH^2+AHcdot CH=(7sqrt{5})^2\CH^2+28CH-245=0\CH=7\AC=AH+CH=28+7=35\AB=sqrt{AC^2-BC^2}=sqrt{35^-(7sqrt{5})^2}=14sqrt{5}\S_{Delta}=cfrac{ABcdot BC}{2}=5cdot 49=245$