Plzz me with all 5 if u me with all 5 and the answrrs be right i will give 40 points and maje u the brainest

If tana tanb=k, show that(1+k)cos(a+b)=(1-k)cos(a-b)

Jack lives on a farm and has a large backyard. the area of his rectangular backyard is of a square mile. if the width of the yard is of a mile, what fraction of a mile is the length of the rectangular backyard?

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ah=4 and hc=1, find bh.