Carcass wrote:
The figure represents the design of a drawbridge that spans a channel 54 meters in width. If the two raisable sections are equal in length and overlap each other by a measure of 2 meters, what will be the clearance width of the bridge in meters, when the sections are raised to an angle of 60 degree ?
A) 25
B) 26
C) 27
D) 28
E) 54
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITIONGRE - Math Book The two raisable sections are equal in length and overlap each other by a measure of 2 metersThe bridge spans a distance of 54 meters.
So, if both sections were 27 meters long, there would be no overlap.
Since the sections overlap by 2 meters, we know that each section is
28 meters long.
So, our diagram looks like this:
If we draw vertical lines from the tips of each section, you see that we have special 30-60-90 triangles hiding in our diagram.
In the each of the right triangles, the hypotenuse has length 28
So, the lengths of the sides opposite the 30 degree angles must be
14.
To find the value of x, we can write the following equation:
14 + x +
14 = 54
Simplify: x + 28 = 54
Subtract 28 from both sides of the equation to get: x = 26
Answer: B
Cheers,
Brent