Which are vertical angles?

If chord ab is congruent to chord cd, then what must be true about ef and eg?

The table below shows the approximate height of an object x seconds after the object was dropped. the function h(x)= -16x^2 +100 models the data in the table. for which value of x would this model make it the least sense to use? a. -2.75 b. 0.25 c. 1.75 d. 2.25

Can someone me and explain..will award brainlest!