Question 929458
A circular arc of length 4 feet subtends a central angle of 180° degrees. Find the radius of the circle in feet.

where,
{{{theta}}} = central angle and {{{r}}} = radius of the circle.


{{{radius = (arc_ length)/theta}}},.... but {{{theta}}}  {{{has}}} to be {{{in}}} RADIANS 

{{{theta=180}}}° => {{{pi=3.14}}} radians

{{{r = (arc_ length)/theta}}}

{{{r= 4ft/3.14}}}

{{{r= 1.27 feet }}}

or this way:

thus,
{{{4ft = 2 * 3.141 * r * (180/360)}}}
=> {{{4ft = cross(2) * 3.141(1/cross(2)) * r}}}

=> {{{4ft = 3.14* r}}}
=> {{{r = 4ft/3.14}}}

={{{r= 1.27feet }}}

or this way:

 {{{radius = Arc_ length / angle}}}   where angle is 
(x*pi/180) 

{{{Arc = 4ft / ((cross(180)*pi)/cross(180)) }}}

{{{Arc = 4ft / pi }}}

{{{Arc = 4ft / (3.14) }}}

={{{ 1.27feet }}}