If the square of the length of the longest side of a triangle is equal to the sum of the squares of the other two sides, then the triangle is a right triangle.
2 is the slope so the slope perpendicular to that is -1/2 (negative reciprocal) -5=-1/2(9) 9*-1/2=-4.5 and -4.5 - 0.5 = -5 so the equation for the line is y=-1/2x -0.5