Math 10 (find angle measure, given trig ratio value)

[sarah.p]

i have no idea how to do this

Find the measure in degrees, where angle A is between 0° and 180°.

a) cos A = (-1/sqrt2)

b) sin A = Sin 130° ( Where A is not equal to 130°)

 

[tkhunny]

Re: Math 10

i have no idea how to do this

Find the measure in degrees, where angle A is between 0° and 180°.

a) cos A = (-1/sqrt2)

b) sin A = Sin 130° ( Where A is not equal to 130°)

a) You should be able to find this value on a chart. It may appear as $\displaystyle \frac{1}{2}\sqrt{2}$ or $\displaystyle \frac{\sqrt{2}}{2}$.

b) Do you have a unit circle? sin(A) = sin(180º - A)

 

[sarah.p]

its like
-1
__
sqrt2

thats all it says..

 

[skeeter]

learn the unit circle

 

[sarah.p]

wow
iv never seen that before, i dont know how to use it

 

[S.Hobden]

how do you use a unit circle?

 

[tkhunny]

You look at it and memorize it. It will help you to decode Quadrants and Reference Angles and Basic Relationships.

If you have a book that has not, or teacher who has not, introduced you to the unit circle, something is seriously wrong. Maybe a genetic experiment that will destroy life as we know it. Well, maybe not that bad.

 

[S.Hobden]

iv never seen it before either

 

[tkhunny]

OK, pka, it's time for another Historical Perspective lesson. Am I out of date on this one? Is the Unit Circle somehow falling out of favor in the academic community? Maybe these examples are anomalous.

 

[pka]

OK, pka, it's time for another Historical Perspective lesson. Am I out of date on this one? Is the Unit Circle somehow falling out of favor in the academic community?

You ask because you know that I am old enough to remember when the unit circle was not used. At one time that concept was reserved for a course called Analytical Trigonometry.
To answer your question, if anything the unit circle approach is practically the only one we now see in textbooks. If anything it is ‘degrees’ that are being relegated to the heap of interesting and historical ideas that are no longer useful. Don’t forget that the basic idea driving modern mathematic education is FUNCTION. We need the unit circle for circular functions.

"Maybe these examples are anomalous." NO THEY ARE NOT.
In the case at hand, I think it is more a matter of who is practicing “mathematics education” than it is “mathematics education” itself. As Skeeter wondered “Is there a teacher present?” It is hard to think there is!

 

[tkhunny]

You ask because you know that I am old enough to remember when the unit circle was not used.

Well, not quite, but I guess we can go with that. :wink:

As always, thanks for the background. No cultural or international flavors on this one?