If point P (shown above) makes one complete revolution around the tria

Question

https://gmatclub.com/forum/download/file.php?id=66493 If point P (shown above) makes one complete revolution around the triangle, what is the length of the path traveled by P? (1) The point P moves in a counterclockwise direction at 1 unit per second and completes one revolution around the triangle in 15 seconds. (2) The height of the triangle is 4. Project DS Butler Data Sufficiency (DS3) For DS butler Questions Click Here 1.jpg

genericUser · Answer

If point P (shown above) makes one complete revolution around the triangle, what is the length of the path traveled by P?

The stem asks the perimenter

(1) The point P moves in a counterclockwise direction at 1 unit per second and completes one revolution around the triangle in 15 seconds.
1*15=15 units 
Sufficient

(2) The height of the triangle is 4.
The triangle is an iscoles one. from top vertex to base we get 2 equal segment.
Right triangle is of type 3,4,5 -> base=6 and then 5+5+6=16
Sufficient

(D)

IanStewart · Answer

At first I thought the triangle must be inscribed in a circle, because you can't make a "revolution" around a triangle, from the definition of that word. The two statements are also inconsistent, assuming the question is just asking for the perimeter of the triangle. What is the source?

genericUser · Answer

IanStewart  can you provide further explanation?
from dictionary -> Revolution:" a procedure or course, as if in a  circuit , back to a starting point." we have a triangular circuit

IanStewart · Answer

The definition of a circuit is "a roughly circular line, route, or movement that starts and finishes at the same place" from Oxford, and "revolution" is only used (in the sense in which the question here is trying to use it) to describe approximately circular motion: https://www.etymonline.com/word/revolution

genericUser · Answer

Ian, I agree with your explanation, in my language circuit refers to a general path, not to a path which possess some desiderable property.
Anyway in the link providing the revolution definition it is stated that revolution can be a recurrent event...
And circuit: "a roughly circular line,  route , or  movement ".
I know continuity, in particula C1, can be importan because if we were to change direction instantaneusly we would use an infinity amount of energy, and it is not possible to do so, but for the sake of the exercise the given speed is constant (avarege theorem of a continuous function representing the speed magnitude) and with the term circuit it is intended a general route. Maybe the situation has been obtained from discrete time measurments and this explain why the circuit is not C1.
But i think this is out of scope.

Thanks for the answer and your time, I always enjoy your posts.
Have a good day

R

zhanbo · Answer

I think the answer to this question is  (A) . Here are a few reasons against condition (2).

* There is no universally agreed definition on what accounts for one complete revolution around a triangle.
* There are three heights in one triangle. 
* Condition (1) and (2) should not contradict with each other. But it is hard to imagine a revolution that is 15 unit. Even if we can, merely knowing one height is insufficient to connect all the dots.

1potato2potato · Answer

zhanbo

The 2 options are inconsistent.

If we go by option A, we get the third side = 5cm ,=> the triangle is equilateral.

All three heights of an equilateral triangle are the same, and is = \sqrt{3}/2 * (side), where side = 5 in our case.

Hence, if A is true, the height cannot be 4.

zhanbo · Answer

So, the OA is D. Can you make sense of it?

If point P (shown above) makes one complete revolution around the tria

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