Answer:
Step-by-step explanation:
1) ΔCPD & ΔEPF
∠CPD = ∠EPF { Vertically opposite angles}
∠CDP = ∠PFE {CD║EF, FD is transversal, Alternate interior angles are equal}
ΔCPD ≈ΔEPF {AA criteria for similarity }
Cross multiply
EF * 15 = 27 * 7.5
EF = 27 * 0.5
EF = 13.5 cm
ii) EF // AB, so Triangles ACB & ECF are similar triangles
AC = 37.5 cm
Answer: 11 is the required number that always divides such differences for the following types of numbers.
Step-by-step explanation:
Take any 3 - digit number, say, 325
On reversing its digit it becomes, 523
On subtracting the smaller of the two numbers from the larger,
we can see that 198 is an even number.
take another number say, 629
On reversing its digit, it becomes = 926
On subtracting , we get that
But 297 is not an even number.
But there is one common in both the cases is that both the differences are divisible by 11.
Hence, 11 is the required number that always divides such differences for the following types of numbers.
Answer:
72 feet from the shorter pole
Step-by-step explanation:
The anchor point that minimizes the total wire length is one that divides the distance between the poles in the same proportion as the pole heights. That is, the two created triangles will be similar.
The shorter pole height as a fraction of the total pole height is ...
18/(18+24) = 3/7
so the anchor distance from the shorter pole as a fraction of the total distance between poles will be the same:
d/168 = 3/7
d = 168·(3/7) = 72
The wire should be anchored 72 feet from the 18 ft pole.
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<em>Comment on the problem</em>
This is equivalent to asking, "where do I place a mirror on the ground so I can see the top of the other pole by looking in the mirror from the top of one pole?" Such a question is answered by reflecting one pole across the plane of the ground and drawing a straight line from its image location to the top of the other pole. Where the line intersects the plane of the ground is where the mirror (or anchor point) should be placed. The "similar triangle" description above is essentially the same approach.
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Alternatively, you can write an equation for the length (L) of the wire as a function of the location of the anchor point:
L = √(18²+x²) + √(24² +(168-x)²)
and then differentiate with respect to x and find the value that makes the derivative zero. That seems much more complicated and error-prone, but it gives the same answer.
