Finding the length of an arc

• Jun 19th 2005, 05:18 AM
Justardms
Finding the length of an arc
:) Hi, just wanted to make sure that I am doing this correctly? Can someone please help me with Finding the length of an arc if the radius is 10" and the central angle is 45 deg. I need to find the answer in terms of pie. Thanks!

Also, I need to find a positive co-terminal angle for 120 deg. and one for pie/5
and a negative co-terminal angle for 420 deg. and one for 3 pie/5

can someone verify what the complement of angle of 20 deg is. and the supplement of an angle of 3pie / 5

How do I change a the following into decimal form? 23 deg. 30' 15"

THANK YOU VERY MUCH
• Jun 19th 2005, 09:10 AM
MathGuru
arc length give radius and angle
Welcom Justardms,

Just a note of advice, try to keep questions to a minimum of 1 or 2 per post as you will get better results. In keeping with my advice I will answer your first question only;)

To find the arc length you can use the equation $\displaystyle s=r\theta$

where s = arc length, r = radius, and $\displaystyle \theta$ = angle in radians

so

$\displaystyle s = 10"(45*\frac{\pi}{180})$
• Jun 19th 2005, 10:49 AM
Justardms
Is this correct?
So is the answer 10pie/4 ? First I have to convert deg. in to rads? correct? which is pie / 4 and then mutiple that by 10? correct? So the Arc lenght is 10 pie / 4? Or would you write 10 times pie / 4? Does it matter!?!?!?! THANKS and thanks for the tip about how to submit questions!
• Jun 19th 2005, 10:51 AM
Justardms
Since it is 10 inches * pie / 4, I am just not sure how I would write that? Thanks again
• Jun 19th 2005, 02:28 PM
Math Help
pi or 3.14
you can either answer with $\displaystyle \frac{10\pi}{4}inches = \frac{5\pi}{2}inches$ or substitue 3.14 for pi and multiply it out to get the answer in inches.