Math math math math 463366544

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Someone answer asap for ! the following statements are true about the coins calvin and sasha have collected. * calvin and sasha has the same amount of money. * calvin has only quarters. * sasha has dimes, nickels, and pennies * calvin has the same number of quarters as sasha has dimes. * sasha has $1.95 in coins that are not dimes. exactly how many quarters does calvin have?

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