Textbook Problem

Finding an Angle In Exercises 107-112, use the result of Exercise 106 to find the angle $\psi$

between the radial and tangent lines to the graph for the indicated value of $\theta$

. Use a graphing utility to graph the polar equation, the radial line, and the tangent line for the indicated value of $\theta$

. Identify the angle $\psi$.

Polar Equation Value of $\theta$

$r=2(1-\cos \theta )$

$\theta =\pi$