positive angles are measured counter-clockwise from the positive x-axis.
100 degrees measure ccw from the positive x-axis terminates in quadrant II ... the value of cosine is negative.
... also, please post trig questions in the trig forum.
Hello, I am using the trig diagram below and I am experiencing some problems. When I enter cos(100) in my calculator, i get a negative number. According to the graph, at 100 degrees going clockwise, cosine should be positive from 90 - 180 degrees. Can someone please explain what I am doing wrong.
Thanks.
positive angles are measured counter-clockwise from the positive x-axis.
100 degrees measure ccw from the positive x-axis terminates in quadrant II ... the value of cosine is negative.
... also, please post trig questions in the trig forum.
In trigonometry, angles measure counterclockwise rotation. 100 degrees is a bit more than the right angle, so rotating the point (1,0) around the origin by 100 degrees counterclockwise puts it in the top-left (second) quadrant, where the cosine is negative. But even if angles were measured clockwise, 100 degrees would be in the bottom-left (third) quadrant, where the cosine is also negative.
once again ... the initial side of an angle in standard position is the positive x-axis.
Standard Position and Reference Angles
In trigonometry, 0 degrees corresponds with a 90-degree bearing (e.g. "east") and 90 degrees corresponds with 0/360 degrees ("north"). It's a little weird why it is defined that way, but it has to do with the way the x- and y-axes are labelled.
I don't get what you're saying.
The unit circle is very simple to understand: angle measure increases as you move counterclockwise. The point corresponds with , corresponds with , and corresponds with .
For any point on the unit circle, and (because sine and cosine are defined as opp/hyp, adj/hyp, where hyp = radius = 1). For example, , because (1,0) corresponds with .
Therefore whenever and whenever .
Yeah, I couldn't understand what computerpublic meant about "completely positive or completely negative" because a number cannot be both positive and negative. He should've said "positive for all x" or "negative for all x."
Anyway, is probably the simplest function. You could also try .