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Jun 15, 2023
 #1
avatar+2447 
+1

 

I drove to the beach at a rate of 40 miles per hour.  If I had driven at a rate of 50 miles per hour instead, then I would have arrived 45 minutes later.  How many miles did I drive?  

 

You mean 45 minutes earlier.  Obviously, if you drive faster, you get there faster.  

 

This problem makes use of

the following relationship:                   Distance = Velocity x Time 

 

                                                           D  =  V • T  

 

case 1                                                 D  =  (40) • (T)  

 

case 2                                                 D  =  (50) • (T – 45)  

 

Since the Distance, D, is the  

same for both cases, let's set       

the "V•T"s equal to each other.             (50)(T – 45)  =  (40)(T)  

 

                                                               50T – 2250  =  40T  

 

Subtract 40T from both sides                  10T – 2250  =  0  

 

Add 2250 to both sides                                       10T  =  2250  

 

Divide both sides by 10                                           T  =  225   (this is in minutes)  

 

Divide minutes by 60 to get hours          225 minutes  =  3.75 hours  

 

Plug this T back into original equation                     D  =  (40 mi/hr) • (3.75 hr)  =  150 miles  

.

Jun 15, 2023
 #3
avatar+2 
0

The angle bisector theorem states that in a triangle, the angle bisector divides the opposite side into segments that are proportional to the lengths of the other two sides.

In triangle PQR, we have PQ = 9, QR = 9, and PR = 9. Since PR is the longest side, angle P is the largest angle in the triangle.

Let's label the length of PX as a and QX as b. Since the angle bisector of angle P intersects QR at point X, we can use the angle bisector theorem to set up the following equation:

PX / QX = PR / QR

a / b = 9 / 9

a / b = 1

Since a and b are in the ratio of 1:1, we can conclude that PX = QX.

Now, let's consider triangle PXY. Since PX = QX, triangle PXY is an isosceles triangle with PX = QX. Additionally, Y is the foot of the perpendicular from X to line PR, which means XY is the altitude of triangle PXY.

In an isosceles triangle, the altitude from the vertex angle bisects the base. Therefore, XY will bisect PR, and we can conclude that PY = YR.

Since PR = 9, PY + YR = PR implies PY + PY = 9, which simplifies to 2PY = 9.

Thus, PY = YR = 9 / 2 = 4.5.

Finally, we can use the Pythagorean theorem in right triangle PXY to find the length of XY:

XY^2 = PX^2 + PY^2

Since PX = PY = 4.5, we have:

XY^2 = 4.5^2 + 4.5^2

XY^2 = 20.25 + 20.25

XY^2 = 40.5

Taking the square root of both sides, we get:

XY = √40.5

Therefore, the length of XY is approximately 6.36 (rounded to two decimal places).

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Jun 15, 2023
 #1
avatar+4 
0

Hello,

 

To prove that PX = 12√6/5 and PY = 12√6/7, we'll use similar triangles and the properties of altitudes in a trapezoid.

Since CP/PD = 1, CP = PD. Let Q be the intersection point of AD and BC.

Consider triangles CPX and DQX. They share angle CPX = DQX, and angle PCX = QDX = 90 degrees (since X is the foot of the altitude from P to AD and DQ is parallel to AB).

Therefore, by AA similarity, triangles CPX and DQX are similar.

We know that AD = 5 and AB = 6, so DQ = (7/5) * AD = 7.2.
Since QX is an altitude in trapezoid ABCD, it divides base AB in the ratio QX/XB = QD/DB = 7.2/4.8 = 3/2.

Thus, XB = (2/5) * AB = 2.4, and PX = XB + XP = 2.4 + 5.6 = 8.   official survey

Now, consider triangles CPY and BQY. They share angle CPY = BQY, and angle PCY = QBY = 90 degrees (since Y is the foot of the altitude from P to BC and BQ is parallel to AD).

Therefore, by AA similarity, triangles CPY and BQY are similar.

We know that BC = 7 and CD = 12, so BQ = (6/7) * BC = 6.857.
Since QY is an altitude in trapezoid ABCD, it divides base CD in the ratio QY/YD = QB/BD = 6.857/5.143 = 1.333.

Thus, YD = (3/4.333) * CD = 8.3, and PY = YD + YP = 8.3 + 3.7 = 12.

Hence, we've proved that PX = 12√6/5 and PY = 12√6/7.

Jun 15, 2023
 #1
avatar+2447 
+1

 

One ordered pair (a,b) satisfies the two equations ab^4 = 48 and ab = 72. What is the value of b in this ordered pair?  

 

 

To find b, consider                                                  ab4  =  48  

 

We will divide both sides by ab.  

 

Since ab=72, we will divide the left side  

by "ab" and the right side by its equal 72.  

                                                                              ab4         48  

                                                                             ——   =   ——  

                                                                              ab           72  

Note that ab4 = (ab) * (b3)  

 

Cancel ab out of the left side.  

Reduce 48/72 on the right side.  

                                                                               b3           2  

                                                                             ——   =   ——  

                                                                                1            3  

 

 

                                                                                 b   =   cube root of (2 / 3)  

.

Jun 15, 2023

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