FIND THE X VALUES OF ALL POINTS, -2PI LESS THAN OR EQUAL TO X LESS THAN OR EQUAL TO 2PI, WHERE Y=X+B IS TANGENT TO Y=X+BSINX.

I KNOW THE ANSWER IS PI/2 AND 3PI/2, BUT WHY AREN'T THEY PLUS OR MINUS.

If they are tangent, they have the same coordinates, and the same slope.

y=x+b
y=x+bsinx

subtracting the first from the second..
0= b(sinx-1)
sinx=1 x=PI/2 or x=-3PI/2

slope:
both 1. The answers are pI/2, -3PI/2