Answer:

Step-by-step explanation:
The vertical component of the initial launch can be found using basic trigonometry. In any right triangle, the sine of an angle is equal to its opposite side divided by the hypotenuse. Let the vertical component at launch be
. The magnitude of
will be the hypotenuse, and the relevant angle is the angle to the horizontal at launch. Since we're given that the angle of elevation is
, we have:
(Recall that
)
Now that we've found the vertical component of the velocity and launch, we can use kinematics equation
to solve this problem, where
is final and initial velocity, respectively,
is acceleration, and
is distance travelled. The only acceleration is acceleration due to gravity, which is approximately
. However, since the projectile is moving up and gravity is pulling down, acceleration should be negative, represent the direction of the acceleration.
What we know:
Solving for
:

The answer is B.about 400, because if you multiply 18 by 24 you get the answer without rounding, and that answer would be 434; once 434 is rounded to the closest possible answer, you get that the answer, which is, as stated before, B. about 400.
In the left hand side, you're multiplying 7.8 by 
In the right hand side, you're multiplying again 7.8 by a mysterious number.
So, the unknown number must be 
Every number remains unchanged when multiplied by 1, so the answer is 3.6
For question 4 the answer is yes and for question 5 the answer is false
3.65x19.8=$72.07 hit that thanks button and 5 star rating plz thankyou!!!!