Please help me on these questions.

An objects motion is described by the equation d= 4sin (pi t) what will the height of the object be at 1.75 seconds?

Cody was 165cm tall on the first day of school this year, which was 10% taller than he was on the first day of school last year.

Random variables x poisson~ ( a) ,y poisson ~ ( a) . x and y are independent. if 2 1, 2 1. u =2x+ y-1, v=2x- y +1. find: ) cov (u ,v ).