The function f(t)=-5t^2+20t+60 models the approximate height of an object t seconds after it is launched. How many seconds does it take the object to hit the ground?

“ a line segment that has the endpoints on the circle and passes through the midpoint is called the diameter. the diameter is twice the size of the radius. a line segment that has its endpoints on the circular border but does not pass through the midpoint is called a chord. a circle is the same as 360 small circle up the number 0 . i hope this .