A circle has a chord that goes from ( 3 pi)/2 3π2 to (7 pi) / 4 7π4 radians on the circle. If the area of the circle is 121 pi 121π, what is the length of the chord?

1 Answer
Mar 24, 2016

See geometric figure:
Chord, bar(AB) = 11sqrt(2)¯¯¯¯¯¯AB=112

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Explanation:

This straight forward problem:
A) Determiner the radius from C_A=piR^2CA=πR2; R =11R=11
Look at the angular displacement between A ->BAB it form
a right angle at the center so trangle AOB is an "isosceles right angle". Thus the ratio of side of an isosceles right triangle is:
s_1:s_2:h=1:1:sqrt(2)s1:s2:h=1:1:2 So for triangle AOD=> a:f:bar(AD)=1:1:sqrt(2)a:f:¯¯¯¯¯¯AD=1:1:2
AD=11sqrt(2)/2AD=1122, thus the chord, AB=11sqrt(2)AB=112