Essential problem 20.1
A curve given by the equation y=sin(pi cosx) find the coordinates of all ht points on the curve for which dy/dx=0
In the explanation it shows that
y'= cos(pi cosx) x (pi cosx)'
y'= cos(pi cosx) x (pisinx)
Therefore sinx or pi cosx must be zero.
However isn't the derivative of cosx, -sinx therefore being -pinsinx and not pisinx?
Here's an answer.
That's a good calculation.But even so
y'= -cos(pi cosx) x (pisinx) = 0
By null factor law,
-cos(pi cosx)=0 or (pi sinx) = 0
so
cos(pi cosx)=0 or (pi sinx) = 0
We're going to end up with the same answer.
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