There is a formula:

Area of segment of circle = r^2 (pi*theta/360) - (sin theta/2), where theta is a measure of corresponding arc in degrees.

Could you please explain how they introduce sine in this formula? why not cosine?

Printable View

- April 20th 2014, 05:52 PMhisajeshPlease explain sine
There is a formula:

Area of segment of circle = r^2 (pi*theta/360) - (sin theta/2), where theta is a measure of corresponding arc in degrees.

Could you please explain how they introduce sine in this formula? why not cosine? - April 20th 2014, 06:06 PMromsekRe: Please explain sine
- April 20th 2014, 09:59 PMprasumRe: Please explain sine
sector area=(pi*(r^2))(theta)/360

sin is introduced here because if you bisect the sector angle theta into two: theta/2,theta/2 then

therefore

sin(theta/2)=(width of half triangle)/radius

so we get side of triangle as 2*r*sin(theta/2)

now you have other two sides of triangle as r

apply heroes formula

then subtract this area from the sector area mentioned above

apply approximations and u will get ur result - April 20th 2014, 10:36 PMromsekRe: Please explain sine
I see... I did the area of a sector. oh well

- April 28th 2014, 01:22 PMhisajeshRe: Please explain sine
@prasum: just curious, when you say "apply heroes formulas" what does that mean?

- April 28th 2014, 02:54 PMromsekRe: Please explain sine