Find value of x?

Brent needs to paint a logo made using two right triangles. the dimensions of the logo are shown below. what is the difference between the area of the large triangle and the area of the small triangle? (1 point) select one: a. 4.5 cm2 b. 8.5 cm2 c. 16.5 cm2 d. 33.0 cm2

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25

Cos^2x+cos^2(120°+x)+cos^2(120°-x)i need this asap. pls me