Leiame tipu C ja kõikide külgede pikkused:

$$C = B + \vec{BC} = (-2; 4) + (-4; 2) = (-6; 6)$$ $$\vec{AB} = B - A = (-2; 4) - (3; -1) = (-5; 5)$$ $$\vec{AC} = C - A = (-6; 6) - (3; -1) = (-9; 7)$$ $$\vert{\vec{AB}}\vert = \sqrt{(-5)^2 + 5^2} = \sqrt{50} = 5\sqrt{2}$$ $$\vert{\vec{AC}}\vert = \sqrt{(-9)^2 + 7^2} = \sqrt{130}$$ $$\vert{\vec{BC}}\vert = \sqrt{(-4)^2 + 2^2} = \sqrt{20} = 2\sqrt{5}$$ Kolmnurga ABC pindala on: $$S = \sqrt{p(p-a)(p-b)(p-c)}$$ $$p = \frac{a + b + c}{2}$$ $$S = \sqrt{6\cdot(6-5\sqrt{2})\cdot(6-\sqrt{130})\cdot(6-2\sqrt{5})}$$ $$S = 5$$

Teeme joonise. Jooniselt on ringijoone keskpunkt umbes koordinaatidel (5; 6):

$$x^2 + y^2 - 10x - 12y = -7.71$$ $$\frac{7.3^2\pi}{5} \approx 34$$