Help!! Unit Circle ?????? (1 Viewer)

[mzmellie]

I am currently studying for my yearly exams that start on Monday and I am really confused by the trigonometry concept of the unit circle

Is anybody able to help clarify this topic as.... our teacher did not teach us a thing!!!

Any help is greatly appreciated

THANK YOU MUCHLY

 

[PC]

Do you really need the unit circle? It's just a way of explaining the trigonometry of angles in the four quadrants.

In the first quadrant, angle x is 0 < x < 90
sin x is always positive
cos x is always positive
tan x is always positive

In the second quadrant, 90 < x < 180
sin x is always positive, and sin x = sin (180 - x)
cos x is always negative, and cos x = - cos (180 - x)
tan x is always negative, and tan x = - tan (180 - x)

In the third quadrant, 180 < x < 270
sin x is always negative, and sin x = - sin (180 + x)
cos x is always negative, and cos x = - cos (180 + x)
tan x is always positive, and tan x = tan (180 + x)

In the fourth quadrant, 270 < x < 360
sin x is always negative, and sin x = - sin (360 - x)
cos x is always positive, and cos x = cos (360 - x)
tan x is always negative, and tan x = - tan (360 - x)

Which gives you the "All Stations To Central" or "Another Stupid Trig Concept"

I suppose the unit circle helps with understanding the ratios are positive and negative at various stages, but you can also get that from the graphs.

 

[yvettemaree47]

My friend Mel and I thank-you so much for the help!

We were told it was in our yearly but the teacher and the textbook didn't explain a thing... but this has helped heaps!

 

[Forbidden.]

Theres "All Sluts Take Cock", then somehow someone came up with "All Stations to China".

 

[unclemilton]

Might be a bit late but the important thing to remember about the unit circle is that all it is is a circle described in parametric form.
i.e.
x = cos(t)
y = sin(t)
where 0 <= t < 2pi
where t is the angle from the positive x axis measured in an anti-clockwise direction.