BrainDen.com - Brain Teasers

# All Activity

1. Today
2. Yesterday

4. ## Square in a circle

If the question is : What is the ratio of the arc length to the perpendicular length from the center of one side of the square to the arc ??? Then assuming diameter of 1" ; the diagonal of the largest square would also be 1 ; this divides the square into 2 isosceles triangles ,whose angles are 45,45,90 In a 45 degree triangle the sides are = Hsin angle or 1 sin 45 = 0.707; therefore i/2 of the lt of a side is 0.353 . The radius is 0.5. 0.5 - 0.353 = the rise 0.147 the distance from arc to square Now the circumference is pie D or 3.14 D, 3.14 (1) = 3.14; acr length 3.14 divided by 4 =0.7853 ratio of arc length to rise ....0.7853/0.147 = 5.342 :1 Previously I assumed the wrong question ,However assuming a diameter of 1" R = 0.5" . I calculated the rise ( r ),which is the distance from the one side of the square at the mid point of that side to the arc or circumference . That value r =0.147 therefore the ratio of r/R = 0.147/0.5 0.147 /0.5 = 1/X; 0.147X = 1x 0.5; X = 1 /0.147; Ratio r / R is 1 /6.802 Quote
5. ## The Dollar Bill

total of \$ 0.75 ; Arrange 4 pennies in a circle around a penny in the center (A ) such that none of the outside pennies are on the same diameter passing thru (A) Let's assume that as we look at our screen (B) is directly below (A) at a distance of the radius ; Moving CW up to the left more than 90 deg is (C) ; continuing CW approx 70 degrees which stops us short of being diametrically opposite (B) is location of (D) : continue CW about 90 degrees for (E). You have 4 triangles which do NOT over lap ABC; ACD ; ADE ; AEB . You then have 6 triangles created by lines from(B) to (D) and from (C) to (E) These triangles being BCD ; BDE; BDA; CDE ; CEA ; CEB. So we have 4 @ 0.10 = \$040 and 6 @ .05 = 0.30 for a total of \$ 0.70 plus the 5 pennies = 75 cents
6. Last week
7. ## Can someone help me figure out the missing numbers?

Preferably how to work it out and not just answers
8. ## The Dollar Bill

nice but not the most that he can earn
9. ## The Dollar Bill

Total of \$ 0.70 ; Arrange 4 pennies in a circle around a penny in the center (A ) such that none of the outside pennies are on the same diameter passing thru (A) Let's assume that as we look at our screen (B) is directly below (A) at a distance of the radius ; Moving CW up to the left more than 90 deg is (C) ; continuing CW approx 70 degrees which stops us short of being diametrically opposite (B) is location of (D) : continue CW about 90 degrees for (E). You have 4 triangles which do NOT over lap ABC; ACD ; ADE ; AEB . You then have 6 triangles created by lines from(B) to (D) and from (C) to (E) These triangles being BCD ; BDE; BDA; CDE ; CEA ; CEB. So we have 4 @ 0.10 = \$040 and 6 @ .05 = 0.30 for a total of \$ 0.70
10. ## Crocodile Sophism

Simple, i would kill the talking crocodile. What........ are we suppose to take a crocodiles word for it that he will answer honestly. but lets play along.. this would be my Answer/response I Predict you will give back my child, (only required A Guess to win) Chess mate. or I predict your death if you eat my chronic ill child who suffers a deadly flesh eating virus gonna need a lawyer for this crocodile.
11. ## The Dollar Bill

Bill has five pennies . He shall make as many triangles as he can to gain more money. For every unique triangle that he creates on a flat table (3 corners at centers of coins) he wins a nickle but for some triangles that dont overlap or intersect with other triangles, he wins a dime. He shall declare the triangles he formed on the table. So Bill can name the identical coins A,B,C,D and E. Note U\$ penny is 1-cent, nickle is 5-cents and dime is 10-cents. How shall Bill put all his coins on the table for greatest earnings?
12. Earlier
13. ## Square in a circle

Maybe one of you answered this question: :) I should have included this pic though...

15. ## Square in a circle

If the question is : What is the ratio of the arc length to the perpendicular length from the center of one side of the square to the arc ??? Then assuming diameter of 1" ; the diagonal of the largest square would also be 1 ; this divides the square into 2 isosceles triangles ,whose angles are 45,45,90 In a 45 degree triangle the sides are = Hsin angle or 1 sin 45 = 0.707; therefore i/2 of the lt of a side is 0.353 . The radius is 0.5. 0.5 - 0.353 = the rise 0.147 the distance from arc to square Now the circumference is pie D or 3.14 D, 3.14 (1) = 3.14; acr length 3.14 divided by 4 =0.7853 ratio of arc length to rise ....0.7853/0.147 = 5.342 :1
16. ## Square in a circle

Suppose i have a circle. I cut off its arcs such that it became the biggest possible square i could make from that circle. This is clear Several clarifications are required: What's the ratio of the edge of the circle .....(1) edge of the circle a) the circumference or b) one of the arcs clarification required: to the middle of the edge of the square ? (assume minimum length) to the radius of the circle. . Is the question : What is the ratio of the arc length to the perpendicular length from the center of one side of the square to the arc ??? Suppose i have a circle. I cut off its arcs such that it became the biggest possible square i could make from that circle. What's the ratio of the edge of the circle to the middle of the edge of the square (assume minimum length) to the radius of the circle.
17. ## Square in a circle

Suppose i have a circle. I cut off its arcs such that it became the biggest possible square i could make from that circle. What's the ratio of the edge of the circle to the middle of the edge of the square (assume minimum length) to the radius of the circle.
18. ## Detective Riddles - School Murders

In a high school, a student falling to death. Police asked a teacher who at the scene. I was walking in the park and heard a scream, then a girl slammed down. I quickly ran to the girl's side and found out that she was dead. After that, I saw a male student on the 5th floor looking at this place. I think the murderer should be him. The police then arrested the male student. The student said: I walking at upstairs that afternoon and suddenly heard screams, so I rushed over. I found that the handrails on the 5th floor fell off. So, I looked down and saw a girl lying on the floor. Then I saw that the teacher was looking at me too. 30 minutes later, police found a note inside the victim's drawer which wrote: Do you want to know what happened to you? See you at the balcony at 5 pm. Police also found a broken eyeglass at the crime scene. After comparison, this eyeglass prescription is much higher than the eyeglass in the victim's house. According to her classmates, except for the class, she does not wear glasses. According to the family, she had lost her memory, she goes to the 5th floor because of the note. Who killed the victims, how did it kill? Can you guess the answer? Try solve it before you see the answer! Answer: https://youtu.be/fStEhri1mnQ

no
20. ## Riddle

Can you guess it? https://youtu.be/lNdfO9WB-6A

22. ## A Threatening Riddle

But of course!
23. ## Miscellaneous logic puzzle from exam

I looked at that for a while. Though it's not much, here's what I got...
24. ## A Threatening Riddle

almost completely sold

Common....
26. ## Miscellaneous logic puzzle from exam

This is a question I stumbled on from an exam. Has anyone got an idea?

Not it
28. ## A Threatening Riddle

trying my damnedest
29. ## Crypto-Anagram #2

You got it! Crypto Rodent whittling professionally (not really "professionally" as the result seen in the picture!) Rolling Stones ... (Don't) Play With Fire (added the "don't" to make a meaningful anagram!)
×