Wait... at 1:10 you list the derivative with respect to t, but it asks for dy/dx. Why couldn't you simply substitute at the beginning like this: x for t^2 in y=cos(t^2) gives y=cos(x) --then derive that? Naturally you'd get the same answer, but it would be quicker AND in terms of x at the end.
yes, of course : )
Wait... at 1:10 you list the derivative with respect to t, but it asks for dy/dx. Why couldn't you simply substitute at the beginning like this: x for t^2 in y=cos(t^2) gives y=cos(x) --then derive that? Naturally you'd get the same answer, but it would be quicker AND in terms of x at the end.