How to find arc length and sector area in radians

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Finding arc length and sector area using radians
0:00 Review of converting degrees to radians and radians to degrees
0:43 200 degrees is how many radians
0:55 315 degrees is how many radians?
2:05 Radian measure of 3Pi/2 is equal to how many degrees?
2:25 Radian measure 2Pi/15 is how many degrees?
3:00 Review of the arc length formulas
3:32 360 degrees = _____ radians
4:12 Review of formula for finding arc length
4:28 Problem 1 Find the length of the intercepted arc of a circle with radius 12 and arc length in radians of 2Pi/3.
5:00 Problem 2 Find the length of the intercepted arc of a circle with radius 9 and arc length in radians of 11Pi/12.
5:55 Find the central angle in radians
6:32 Find central angle of a circle with radius 100 and arc length is 310.
7:06 Finding sector area in degrees
8:00 Find sector area of a circle with radius of 12 and central angle measure of 2pi/3.
8:20 Find sector area of a circle with a radius of 9inches and central angle of 11pi/12
10:40 Find the radius of a circle.
11:10 Find the radius of a circle with a arc length of 150m^2 and a central angle measure of 3pi/4
13:10 A circle has a sector area of 175 inches^2 and a theta of 5pi/6. What is the radius?

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[ArturoGarzaID]

Why didn't you use pi in the second examples that you did? You said you don't always have to use a pi. Can you explain? Could you have used one anyways? That kind of threw me off.

[rahulparmar]

Q: find area of segment if r=5 arc length =3.5,
Book says in solution ans is (r*s) 1/2. I don't understand how did they got this expression?? Plz help madam

[mikeysuperboom]

315/5 its not 60, your calculator was right but you wrote down wrong value. Thats why people may get confused. The answer for the second warmup question is wrong. :D