Start by graphing the functions: We can see that they intersect at two places. Set the equations equal: cos *θ* = sin *θ* This is true when Then . One of our points of intersection is . We can see from the picture that these graphs also intersect at the origin, but we can't find that by solving the equation cos *θ* = sin *θ* because different values of θ make cos *θ* and sin* θ* equal to 0. This doesn't matter since the point (0, *θ*) is the same point no matter what *θ* is. We may as well call the point *r* = 0 and not worry about *θ*. This point, *r* = 0, is the second intersection point. |