Length of chord ?

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Length of chord ?

by amp0201 » Tue May 01, 2012 6:31 pm
Q. The points R, T, and U lie on a circle that has radius 4. If the length of arc RTU is 4*(pi)/3, what is the length of line segment RU?

A. 4/3 B. 8/3 C. 3 D. 4 E. 6
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by Anurag@Gurome » Tue May 01, 2012 7:33 pm
amp0201 wrote:Q. The points R, T, and U lie on a circle that has radius 4. If the length of arc RTU is 4*(pi)/3, what is the length of line segment RU?

A. 4/3 B. 8/3 C. 3 D. 4 E. 6
Circumference of the circle = 2(pi)(4) = 8(pi)
Let x be the angle subtended at the center of circle.
Then (x)(8)(pi)/360 = 4(pi)/3
x = 60, now RC and RU are equal so angles CRU and RUC should be equal. Hence, triangle RCU is an equilateral triangle with each angle 60º.

So, RU = 4

The correct answer is D.
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