Find the equation of the tangent line to the curve y=?1tan(x) at the point (?4,?1). The equation of the tangent line is You may enter the equation in any form. Use your calculator to draw the function and the tangent line in the same window. Solution y\' = -(1+tan^2(x)) = -(1 + 1) = -2 So the tangent line equation is: y - (-1) = -2(x - /4) or y = -2x + /2 - 1.