Probem40+Abby,+Yutong

F= µW/(µsin(ø)+cos(ø)) domain of ø is 0 and pie/2 d(F) =( (µsin(ø)+cos(ø))-µW(µcos(ø)-sin(ø)) )/ (µsin(ø)+cos(ø))^2Check this -- you are missing a μ in the numerator (in using the quotient rule). One suggestion: why not think of this as μW{μsinϴ + cos ϴ}^(-1), and then just use the product rule? (and chain rule, of course). It works out okay. 0=( (µsin(ø)+cos(ø))-µW(µcos(ø)-sin(ø)) )/ (µsin(ø)+cos(ø))^2 0=(µsin(ø)+cos(ø))-µW(µcos(ø)-sin(ø)) µsin(ø)+cos(ø)-µ^2wcos(ø)+µwsin(ø)= 0
 * 40

Keep going -- my answer was ϴ in terms of inverse tan of μ so not pretty!