Need Math Help!

[PreludeVT]

Ok, I am trying to find this out for a friend. Can someone tell me the formula for finding an Arc Length if you are given an angle and the radius of a circle. After that, what is the formula or steps that are needed to find the angle between that straight line and the curve line of a circle. Thanks.

 

[Urinal Mint]

Arc length = 2*pi*r*(angle/360)

What about the tangent line do you want to know?

 

[Cattlegod]

not 100% sure here, pulling this out of the attic in the head, but arc length from the radius and angle should be:

Length = 2*(PI)*R * (angle/360)

 

[Cattlegod]

hehe not quite fast enough at least i said the same thing

 

[Urinal Mint]

Cattlegod:

 

[Capn]

s=alpha*r (alpha in radians)

 

[PreludeVT]

top

 

[Capn]

for the tangent line part, you need a better description of what you're looking for. There's an infinite number of tangent lines to any arc. Is the arc center at the origin? Do you want tangent line at angle? Details, we need details.

 

[PreludeVT]

ok, here are the exact words from my friend.

friend: the slope should be always the same, shouldn't it?
friend: u know how the tangent line is always perpendicular to the cneter? if you draw a line?
friend: i just want the angle between the tangent line and the arc

i don't know if it is much help. Thanks

 

[PreludeVT]

top

 

[Capn]

your friend seems confused, there's no angle between the tangent and the arc. Sounds like what he's looking for is the angle between a line from the center of the arc to any point on the arc and the tangent line through that same point, and they are always perpendicular.