(45-15)*(5/60)*(360/60)
=30*(1/12)*6
=15度
(45-15)*(360/60)
=30*6
=180度
(9*5-45+45*(5/60))*(360/60)
=45*(1/12)*6
=22.5度
从9点15分到9点45分时针转了15度,分针转了180度,此时时针与分针的夹角为22.5度.