posted by Sagar .
consider the following.
y = cos 3x
point (pi/4, -square root of 2/2)
(a) Find an equation of the tangent line to the graph of f at the given point. (Let x be the independent variable and y be the dependent variable.)
first, find the slope of the tangent line anywhere:
y' = -3sin(3x)
so, at x=π/4, y = -3sin(3π/4) = -3/√2
Now you have a point and a slope, so the line is
y + 1/√2 = -3/√2 (x - π/4)