Find the slope of the tangent line when theta equals pi over 4 for the polar graph r = 4 cos θ.

Question

Find the slope of the tangent line when  for the polar graph r = 4 cos θ

A	1
B	-1
C	0
D

Answer 1

The graph is a circle radius 2 and center (2,0)

The derivative dy/dx (in Cartesian co-ordinates) when x=y (theta=pi/4) is (x-2) as long as x is not 0

The line x=y intersects the circle at x=1 where the derivative is -1......so answer B