want to find out Angle?

[Smily]

Hi Guys,

I want to clear kindergarden maths doubt

I want to find out the angle...if you see the picture will know exactly what I mean..

value of x and r are given I want to find out A value what is the formulae for that....Pls give me a clue..

Smily

[axion_sa]

A = (360x) / (Pi * (r * 2))

working off that x would be the angle / 360 multiplied by the circumference.

_{i think}

[Smily]

hi,

If x=3 and r = 6

means

A=360*3/(22/7*6*6)
=1080 * 113.14

A =122191.2

Is it right? if I divide A/360 => 122191.2/360

answer is 339.42 => I do not think so

pls help me!

[noble]

if you know the arc length (x) and the radius (r) then the angle
is x/r

in this kind of equation it's commonly expressed as

s = r*theta

where s is the arc length, r is the radius, and theta is the internal
angle

[axion_sa]

actually...

Let x = 3
Let r = 6

Circumference = Pi * (r * 2)
= (22/7) * (6 * 2)
= 37.7143 (4dp)

A = 360x / Circumference
= (360 * 3) / 37.7143
= 1080 / 37.7143
= 28.6364

CHECK:
Length of Arc = (Angle / 360) * Circumference
x = (28.6364 / 360) * 37.7143
x = 0.079545 (recurring 5) * 37.7143
x = 2.99828

use a calculator, don't take it to 4dp and u'll find that the equation brings it 3.0000049458 (recurring 8).
i think the 4.9458 * 10^-6 is a bit insignificant

If x=3 and r = 6

means

A=360*3/(22/7*6*6) -- nu uh, supposed be 22/7 * (6 *2)
=1080 * 113.14 -- supposed to be 1080 / (22/7) * (6 *2)

A =122191.2 -- therefore wrong

am i wrong still?

[Smily]

thx axion - it worths million dollars

smily

[noble]

why all the extra work?

x = r*Angle

[Guv]

AngleRadians = ArcLength / Radius

The above gives angle in radians.

AngleDegrees = 180 * ArcLength / pi * Radius

[noble]

of course it's in radians, we don't work with degrees