https://web2.0calc.com/questions/geometry-problem_14 ok so i found this thing(and cphill is back on the top users!) and i wanted to provide my solution, solution below. Also cphill if you see this i got a different answer from you idk why.

 Feb 15, 2022

so draw a line from b to c. ad and bc will intersect at the center of the circle. call that point O. the ratio of angle aob(80 degrees) to a full circle(360 degrees) is the same as the ratio of AB to the cirumference of the circle. in the end, you get 8pi..





i just realizing i was calculating the arc AB because the question on alcumus was asking that

 Feb 15, 2022

the guest's were both me i forgot to login lol

 Feb 15, 2022

I got the same answer as CPhill. 


Since the radii are equal length, thus the other angle is 50 degrees, and the central angle is 80 degrees. We can use law of cosines, so cos 80 is approximately 0.17, and the radii are 18 units each.

That means the length of the chord^2 = 18^2 + 18^2 - 2*18*18*cos80 degrees.

Length of chord^2 = 648 - 648*0.17.

We get:


Length of chord^2 = 535.476.


Length of chord is 23.14.


Thus, in terms of pi it would be approximately 7.3658pi.



 Feb 15, 2022

we were calculating different things i was calculating the arc ab and cphill was calculating the line ab

 Feb 16, 2022

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