Each side of a regular octagon has lengths s. Find a formula for the distance d between the parallel sides of the octagon

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

50 plz, given the system of equations, match the following items. x + 3 y = 5 x - 3 y = -1 a) x-determinant b) y-determinant c) system determinant match the following to the pictures below.

Money off coupons have been circulated to 300 households. only 2/5 of these were redeemed (used) in the local supermarket to get a free shampoo. what fraction of coupons were unused? (ps: write how you got the answer)