The length of a rectangle is increasing at a rate of 9 cm/s and its width is increasing at a rate of 8 cm/s. When the length is 7 cm and the width is 4 cm, how fast is the area of the rectangle increasing?

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

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)

Astocks price gained 3% in april and 5% in may and then lost 4% in june and 1% in july during which month did the stocks price change the most