Points (2 ,2 )(2,2) and (8 ,1 )(8,1) are (5 pi)/6 5π6 radians apart on a circle. What is the shortest arc length between the points?

1 Answer
Jan 27, 2018

Shorter arc length between the points is 8.25 8.25 unit.

Explanation:

Distance between two points (2,2) and (8,1) (2,2)and(8,1) is

D= sqrt ((x_1-x_2)^2+(y_1-y_2)^2) =sqrt ((2-8)^2+(2-1)^2D=(x1x2)2+(y1y2)2=(28)2+(21)2 or

D=sqrt37 ~~ 6.08D=376.08 unit. So, chord length is L_c=6.08Lc=6.08 unit.

Formula for the length of a chord is L_c= 2r sin (theta/2)Lc=2rsin(θ2)

where rr is the radius of the circle and thetaθ is the angle

subtended at the center by the chord.

theta =(5pi)/6=(5*180)/6=150^0 ; theta/2=75^0θ=5π6=51806=1500;θ2=750

6.08 = 2*r *sin75 or r = 6.08/(2*sin75)= 3.156.08=2rsin75orr=6.082sin75=3.15 unit.

Arc length is L_a= 2* pi * r*theta/360=2*pi*3.15*150/360La=2πrθ360=2π3.15150360 or

L_a ~~ 8.25La8.25 unit. Shorter arc length between the points is

8.25 8.25 unit. [Ans]