CAN SOMEONE TELL ME WHAT (HIJ) IS IN THIS CIRCLE PLEASE

The midpoints of the sides of the large square are joined to form a smaller square. what is the area of the smaller square

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

If 30 lb of rice and 30 lb of potatoes cost ? $27.60? , and 20 lb of rice and 12 lb of potatoes cost ? $15.04? , how much will 10 lb of rice and 50 lb of potatoes? cost?