SOMEONE PLEASE HELP I have been on this question for over 20 minutes!!

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)

Solve the triangle. a = 21°, c = 105°, c = 5

A.s.a.! similarity in right triangles, refer to the figure to complete this proportionc/a = a/? a.) cb.) hc.) rd.) s