Mathematics, 23.10.2020 15:20 Arealbot

Jivesh is analyzing the flight of a few of his model rockets with various equations. In each equation, h is the height of the rocket in centimeters, and the rocket was fired from the ground at time t = 0, where t is measured in seconds. For Jivesh's Model A rocket, he uses the equation h = −40t2 + 120t. When is the height of the Model A rocket 90 centimeters? Round your answers to the nearest hundredth. After t ≈ seconds, the rocket will have reached a height of 90 centimeters.

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Answer from: dxpebetty64

After 1.5 seconds, the rocket will have reached a height of 90 centimeters.

Step-by-step explanation:

You know that for Jivesh's Model A rocket, he uses the equation:

h = −40*t² + 120*t

You want to know at what time the height of the model A rocket is 90 centimeters, that is, at what time t the height of the rocket h has a value of 90. Substituting this value in the equation you obtain:

90= −40*t² + 120*t

A quadratic equation has the general form:

a*x² + b*x +c= 0

where a, b and c are known values and a cannot be 0.

Taking the equation for Jivesh's model A rocket to that form, you get:

-40*t² +120*t - 90= 0

The roots of a quadratic equation are the values of the unknown that satisfy the equation. And solving a quadratic equation is finding the roots of the equation. For this you use the formula:

$\frac{-b+-\sqrt{b^{2}-4*a*c } }{2*a}$

In this case, solving the equation is calculating the values of t, that is, you find the moment when the rocket will have reached a height of 90 centimeters.

Being a= -40, b=120 and c= -90, then

$\frac{-120+-\sqrt{120^{2}-4*(-40)*(-90) } }{2*(-40)}$

$\frac{-120+-\sqrt{14,400-14,400} }{2*(-40)}$

$\frac{-120+-\sqrt{0} }{2*(-40)}$

$\frac{-120+-0 }{2*(-40)}$

$\frac{-120 }{2*(-40)}=\frac{-120}{-80} =1.5$

This means that after 1.5 seconds, the rocket will have reached a height of 90 centimeters.

Answer from: Quest

.19875994384

step-by-step explanation:

1699/ 8548

Answer from: Quest

proofs involving isosceles triangles often require special consideration because an isosceles triangle has several distinct properties that do not apply to normal triangles.(more about triangle types) therefore, when you are trying to prove that two triangles are congruent, and one or both triangles, are isosceles you have a few theorems that you can use to make your life easier.

step-by-step explanation:

an isosceles triangle has two congruent sides and two congruent angles. the congruent angles are called the base angles and the other angle is known as the vertex angle. ∠bac and ∠bca are the base angles of the triangle picture on the left. the vertex angle is ∠abc

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