Does anybody know anything about coterminal angles?

Question

I have a pre-calculus question that i cant answer and i need help... the question is:
Find a negative (bold word) angle theta that is coterminal to 2pi/5.

I hope it makes sense.

If you cant get this answer then at least tell me how to find a coterminal angle please (or websites that might help).. Thanks!

Answer 1

Coterminal angles are angles that end up in the same spot.

For example, if you start out facing east, you can turn left 90 degrees, or 450 degrees, or 810 degrees, or 1170 degrees, and in each of these cases you'll end up facing north. That makes these angles coterminal. The bigger numbers make you spin around more, but as long as you end up facing the exact same direction, the angles are coterminal.

In other words: you can find a coterminal angle by adding or subtracting any whole number multiple of 360 degrees.

Using radian measure, one full revolution is 2 pi, not 360 degrees. Thus, you can find coterminal angles by adding or subtracting any whole number multiple of 2 pi.

So, to answer the question, just start with your (2/5)*pi angle, and subtract 2 pi from that. You end up with (-8/5)*pi, which is a negative angle coterminal with 2/5 pi.

Answer 2

Coterminal angles are angles that share an initial side. For example, if you have a 30 degree angle (measuring from the horizontal position), then the coterminal angles for that particular angle would be -330 and 750 would be the coterminal angles. There are actually an infinite number of coterminal angles. Heres a website for a pict of coterminal angles.

http://www.mathwords.com/c/coterminal.htm

btw, the angle to your problem is express is express in radians, just in case you didnt know.
For that just subtract 2pi then you got your answer. Dont forget to make it negative.

Answer 3

Ok i took pre calc and Im in Calculus right now, but im rusty on that stuff so here it goes. The coterminal angle is the angle that ends after you do rotations from your orginal angle which is the straight line from the origin running on top of the x-axis to the right. so now you have to take 2pi/5 and figure out its angle of degree. if you divide out you get something close to 1.25836 and you take that times 180 or 360 im not sure but that would give you the number of rotations in a counterclockwise direction to find your coterminal angle. so its either 226.5 or 453.2 and that would mean you go into the III quadrant or the II quadrant and draw your angle with a 46* angle in III from the top or a 3* angle in II from the middle. I think its close i hope it helps.

Answer 4

Check out
http://www.analyzemath.com/Angle/coterminal_angle.html

It's pretty basic and you **will** be using this quite a bit later on in Geometry.


Doug

Answer 5

thats wird!!!!!!!!!!!