Q2 . 4 marks The revenue from the sale of ice cream at time t measured in months from | January 2021, is given by R ( t ) = 60 + 40 sin ( IIt - II ) for Ost= 12 . 6 2 " ) Find the amplitude and period of R(K ) . 6 ) sketch the graph of RIK ) for Oct = 12 . ( ) what is the marginal revenue on I April 2021