Look at the picture. Use the Pythagorean theorem: h - a hypotenuse [tex]h^2=4^2+2^2\\\\h^2=16+4\\\\h^2=20\to h=\sqrt{20}\\\\h=\sqrt{4\cdot5}\\\\h=2\sqrt5[/tex] Answer: The length of the hypotenuse is equal 2√5. Other method. Use the formula of the length of the segment AB: [tex]A(x_A;\ y_A);\ B(x_B;\ y_B)\\\\|AB|=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2}[/tex] We have: [tex]A(4;\ 2);\ B(8;\ 4)\\\\|AB|=\sqrt{(8-4)^2+(4-2)^2}=\sqrt{4^2+2^2}\\\\=\sqrt{16+4}=\sqrt{20}=\sqrt{4\cdot5}=2\sqrt5[/tex]
