Consider the following.

$w=cos(x-y),x=t^2,y=4$

$($a$)$ Find $\frac{dw}{dt}$ by using the appropriate Ovain Bule. $($Enter your andwer in terms of $t.)\frac{dw}{dt}=$

$(0)$ Find $\frac{dw}{dt}$ by converting w to a function of $t$ before differentiating. $($Enter your andwer in berms of $t.)\frac{dw}{dt}=$