Thinner in the center that at the edges; virtual image smaller.

lens

concave mirror

concave lenses

convex lens

The correct answer is concave lenses.

Explanation:

A concave lens refers to a lens, which exhibits at least one surface that bends inwardly. It is a diverging lens, which signifies that it disperses out the light rays that have been refracted via it. A concave lens is thinner at its midpoint in comparison to its edges and has an application in correcting short-sightedness.  

The formation of an image by a concave lens is virtual, which signifies that it will seem to be farther away than it actually is, and thus, smaller in comparison to the object itself.  

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.