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For a pair of similar triangles, corresponding sides are always congruent.<br> True or false?

baherus [9]

That's false.
For similar triangles, corresponding angles are congruent.
Corresponding sides are in the same ratio but rarely congruent.
(They're congruent only if the ratio is ' 1 ', i.e. the triangles are congruent
as well as being similar.)

6 0

3 years ago

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A rock thrown vertically upward from the surface of the moon at a velocity of 36m/sec reaches a height of s = 36t - 0.8 t^2 met

Verdich [7]

Answer:

a. The rock's velocity is $v(t)=36-1.6t \:{(m/s)}$ and the acceleration is $a(t)=-1.6 \:{(m/s^2)}$

b. It takes 22.5 seconds to reach the highest point.

c. The rock goes up to 405 m.

d. It reach half its maximum height when time is 6.59 s or 38.41 s.

e. The rock is aloft for 45 seconds.

Step-by-step explanation:

Velocity is defined as the rate of change of position or the rate of displacement. $v(t)=\frac{ds}{dt}$
Acceleration is defined as the rate of change of velocity. $a(t)=\frac{dv}{dt}$

a.

The rock's velocity is the derivative of the height function $s(t) = 36t - 0.8 t^2$

$v(t)=\frac{d}{dt}(36t - 0.8 t^2) \\\\\mathrm{Apply\:the\:Sum/Difference\:Rule}:\quad \left(f\pm g\right)'=f\:'\pm g'\\\\v(t)=\frac{d}{dt}\left(36t\right)-\frac{d}{dt}\left(0.8t^2\right)\\\\v(t)=36-1.6t$

The rock's acceleration is the derivative of the velocity function $v(t)=36-1.6t$

$a(t)=\frac{d}{dt}(36-1.6t)\\\\a(t)=-1.6$

b. The rock will reach its highest point when the velocity becomes zero.

$v(t)=36-1.6t=0\\36\cdot \:10-1.6t\cdot \:10=0\cdot \:10\\360-16t=0\\360-16t-360=0-360\\-16t=-360\\t=\frac{45}{2}=22.5$

It takes 22.5 seconds to reach the highest point.

c. The rock reach its highest point when t = 22.5 s

Thus

$s(22.5) = 36(22.5) - 0.8 (22.5)^2\\s(22.5) =405$

So the rock goes up to 405 m.

d. The maximum height is 405 m. So the half of its maximum height = $\frac{405}{2} =202.5 \:m$

To find the time it reach half its maximum height, we need to solve

$36t - 0.8 t^2=202.5\\36t\cdot \:10-0.8t^2\cdot \:10=202.5\cdot \:10\\360t-8t^2=2025\\360t-8t^2-2025=2025-2025\\-8t^2+360t-2025=0$

For a quadratic equation of the form $ax^2+bx+c=0$ the solutions are

$x_{1,\:2}=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

$\mathrm{For\:}\quad a=-8,\:b=360,\:c=-2025:\\\\t=\frac{-360+\sqrt{360^2-4\left(-8\right)\left(-2025\right)}}{2\left(-8\right)}=\frac{45\left(2-\sqrt{2}\right)}{4}\approx 6.59\\\\t=\frac{-360-\sqrt{360^2-4\left(-8\right)\left(-2025\right)}}{2\left(-8\right)}=\frac{45\left(2+\sqrt{2}\right)}{4}\approx 38.41$

It reach half its maximum height when time is 6.59 s or 38.41 s.

e. It is aloft until s(t) = 0 again

$36t - 0.8 t^2=0\\\\\mathrm{Factor\:}36t-0.8t^2\rightarrow -t\left(0.8t-36\right)\\\\\mathrm{The\:solutions\:to\:the\:quadratic\:equation\:are:}\\\\t=0,\:t=45$

The rock is aloft for 45 seconds.

5 0

3 years ago

Distance: Jack and Jill start from the same point and walk in'opposite directions. Jack

777dan777 [17]

Answer:

t = 6 km/hour

And, J would be 4 km per hour

Step-by-step explanation:

Let us assume the speed of Tom be T

And, the Speed of Jim be J

Given that

T - J = 2 km /hr ...........(i)

After 3 hours distance between them = 30 km

As they are walking in the opposite direction

Thus,

Net speed =T + J

L ÷ (T+J) = 3

30 ÷ (T+J) = 3

T +J =10 ..............(2)

After solving these two equations

2T = 12

t = 6 km/hour

And, J would be 4 km per hour

6 0

3 years ago

at maximum speed, an airplane travels 1720 miles against th wind in 5 hours. Flying with the wind, the plane can travel the same

iragen [17]

Answer:

x = 387

Step-by-step explanation:

The wind acts in the opposite direction to the plane when the time is longer.

The wind acts in the same direction as the plane when the time is shorter.

Equation

d = r*t

Givens

d = 1720
x = plane's speed
y = wind speed
t1 = 5 hours
t2 = 4 hours.

Substitution

d = (x + y) * t
1720 = (x + y) * 4
1720 = (x - y) * 5

Since the two distances are the same, you can equate the right hand sides.

(x + y) * 4 = (x - y)*5 Remove the brackets.
4x + 4y = 5x - 5y Add 5y to both sides
4x + 4y + 5y = 5x - 5y + 5y Combine all the terms.
4x + 9y = 5x Subtract 4x from both sides
9y + 4x - 4x = 5x - 4x Combine
9y = x

Now use one of the given equations with the distance

1720 = (x + y)*4 Substitute 9y for x
1720 = (9y + y) * 4 Combine
1720 = 10y * 4 Multiply the right
1720 = 40y Divide by 40
1720/40 = 40y/40 Do the division
43 = y y = wind speek
9y = x x = 9*y
9*43 = x
x = 387 miles per hour.

4 0

3 years ago

Two planes leave an airport the same time and travel in opposite directions. one plane averages 300 miles per hour, and the othe

vekshin1

In 3 hours, the two planes will be 2,700 miles apart.

If in one hour, the planes get 900 miles apart, it will take 3 hours to become 2,700 miles apart.

《----- and -----》 Indicatethe planes moving in opposite directions.

The number indicate the distance traveled.

The amount of times the number is repeated indicates the amount of hours flown (ex.: 50+50+50+50 would indicate 4 hours flown because there are 4 50s in the sequence).

So
《-----300 + 600-----》
=900 miles in one hour

《------300+300 and 600+600-----》
=1,800 miles in 2 hours

《-----300+300+300 and 600+600+600-----》
=2,700 miles in 3 hours

5 0

3 years ago

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