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The figure below shows a hinged structure made up of 12 sticks. The structure can be elongated and compressed by changing the angle A... -
1. Pointing to a man, a woman said, “His mother is the only daughter of my mother.” How is the woman related to the man? a. Mother b. Dau...
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Consecutive percent increase and decrease: 1. x percent of y percent of z is decreased by y percent. What is the result? (A) ...
Solution please?
ReplyDeleteC 400
ReplyDeleteHow u find the ans
ReplyDeleteAhh... another good ol' math related mental ability question.
ReplyDeleteBy the way "iamjayanth" your answer is wrong. The correct answer is 450(Option D).
Now, the question is how can one get it right?
Just join all the diagonals between the tilted squares(diamonds) between the 150sqrt(6) markings. For each square, we have the diagonal length as 30sqrt(6) (just look at figure and you will find that the lengths of BE, EH, HK, etc. are the same so we have 5 such repetitions so just divide by 5).
From that square again divide the diagonal into half. Considering we have selected the first square/diamond BDEC... Let the mid point be O.
We have BO=OE=15sqrt(6)
Complete the triangle BOD. From there it can be seen clearly that angle OBD is 45(now don't ask me how... I'm not going to teach you everything... best advice is to just brush up your math because these simple stuff have been completed in earlier classes).
Now considering triangle BOD calculate BD using Pythagoras theorem.(You know the length of OD because it is an inverted square/diamond, which is the same as BO(property of diagonals of a square))
Now after reducing the angle between ABR to 60 degrees, the angle OBD becomes 30 degrees.
Apply trigonometry here,
Cos30=BO/BD
BO=(BD)cos30= 45 units
So, the total length BE=2(BO)= 90 units
Again 5 such repetitions occur as explained earlier.
So for length BQ, just multiply it by 5.
BQ = 5(BE) = 5*90 = 450 units
That's the answer to your question.