What is the instantaneous rate of change at cos pi/4?
2 answers
-1/root2
for what function ??
if it is y = cosx
then dy/dx = -sinx
and -sin(π/4) = -1/√2
so you are correct if y =cosx
if it is y = cosx
then dy/dx = -sinx
and -sin(π/4) = -1/√2
so you are correct if y =cosx