Which statement justifies why ∠ebc measures 90°? given: angles abd and dbc are complementary a linear pair is two adjacent, supplementary angles. the sum of the measures of complementary angles is 90 degrees. if two angles are vertical angles, then they are congruent. alternate interior angles are congruent.

geometry! !

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 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)