Let f be a function continuous and differentiable for all real numbers.Given a point x1, let L be the tangent to the curve y=f(x) at the point (x1,f(x1)).a. Show that for all x2, there exists a point c between x1 and x2 such that|L(x2)-f(x2)|=|f'(c)-f'(x1)||x2-x1|b. Find the equation of the tangent to the curve y=f(x)=cos(2x) at the point where x=1.c. Hence approximate the value of f(1.1).d. Use your result from part (a) to show that the error in your approximation cannot be more than 0.1.Hint: 0|sina-sinb|2 for all real a and b.