Question

The sign of the value of cos 112.5 degrees is... How do I go about solving this?

Answer 1

Here's two ways to know this, first is, just plug it into a calculator and it'll let you know whether or not it's negative or positive.
The second way http://en.wikipedia.org/wiki/File:Unit_circle_angles_color.svg
If you remember that the cos of an angle is the x value, and know that 112.5 degrees is in quadrant 2, which is >90 degrees but < 180 degrees, where x is negative, also occurring in quadrant 3, >180 degrees and < 270 degrees.

Answer 2

When I plugged cos(112.5) into the calculator I got -0.38

Answer 3

get the answer from the quadrant system, this angle lies in 2nd quadrant, so we can find the signs remembring it! its quite easy to learn

Answer 4

What's the second way of solving? When I clicked the link I just see the Unit Circle. Is there a way to use the Unit Circle to solve this? (:

Answer 5

It's asking for the sign of it, I'm assuming it means whether or not it is positive or negative, coming from the way the question looks. Also, yes there is a way, memorizing at the very least, what I wrote after I posted the hyperlink, that's really just to know where everything is positive and negative in this case.

Answer 6

Oh, alrighty. Well thank you (:

Answer 7

I thought it was asking for like a specific number Lol I didn't realize how plane that question was

Answer 8

All STUDENTS TAKE COFFE
(1st)(2nd) (3rd) (4th)

Answer 9

Lol! I like that (: My teacher taught us All Students Take Calculus

Answer 10

well, coffe is better

Answer 11

I agree Lol

Answer 12

:)