The slope of a line is given by the change in y coordinates over the change in x coordinate. The slope of line DE will be (4 - -3)/ (7-1) = 7/6 If M1 and M2 are slopes of two perpendicular lines at a point then M1× M2 = -1 Thus, the slope of a perpendicular to line DE will be -6/7.
The tangent line is perpendicular to the radius from the center of the circle to the point of tangency. ΔDCE is similar to ΔDBA DC/DB=DE/DA 15/50=DE/40 DE=12
