Y = 14 - 3x ; domain -6,5,13 find the range

Which shows the image of rectangle abcd after the rotation (x, y) → (–y, x)?

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.