Answer:
9 seconds
Step-by-step explanation:
The complete question is
The altitude of an object, d, can be modeled using the equation below:
d=-16t^2 +vt+h
from the edge of a 486 foot cliff, Peyton shot an arrow over the ocean with an initial upward velocity of 90 feet per second. In how many seconds will the arrow reach the water below?
Let
d ----> the altitude of an object in feet
t ---> the time in seconds
v ---> initial velocity in ft per second
h ---> initial height of an object in feet
we have
we know that
When the arrow reach the water the value of d is equal to zero
we have
substitute the values and solve for t
Multiply by -1 both sides
The formula to solve a quadratic equation of the form is equal to
in this problem we have
substitute in the formula
the solution is t=9 sec
see the attached figure to better understand the problem
