Answer:
dy/dx = -1 /√(1 - x^2).
Step-by-step explanation:
y = arccos x.
So x = cos y
dx / dy = - sin y
dy / dx = -1 / sin y
But sin y = √( 1 - cos^2 y)
But cos y = x , so cos^2y = x^2
Therefore
dy/dx = -1 / √(1 - x^2).