sine of an angle: If sin(A) = 1/2, what is measure of A?

C

CMouser

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I was absent this week and i am not sure at all on how to do this. Thanks so much.
If sin A is 1/2 what is measure of angle A
 
Re: sin of an angle

while you're at it, you might as well learn the unit circle (left/right/up/down/forward/backward/inside out) ... you're gonna' need it.

720px-Unit_circle_angles.svg.png
 
Pretty scary picture for someone who's having trouble with finding the angle when sin x = 1/2.

It would help if they knew that the ordered pairs are in the form (cos x, sin x).

If you have a calculator with inverse sin (sin[sup:p8y5ogqz]-1[/sup:p8y5ogqz]), then simply punch sin[sup:p8y5ogqz]-1[/sup:p8y5ogqz](1/2) and enter. The answer should be 30 deg, right where the unit circle says it is.
 
masters said:
Pretty scary picture for someone who's having trouble with finding the angle when sin x = 1/2.
Click to expand...
If the student is having trouble memorizing the table, then the picture might be helpful. And knowing this information is, as the tutor implied, extremely useful.

masters said:
If you have a calculator with inverse sin (sin[sup:3qkghv6u]-1[/sup:3qkghv6u]), then simply punch sin[sup:3qkghv6u]-1[/sup:3qkghv6u](1/2) and enter. The answer should be 30 deg, right where the unit circle says it is.
Click to expand...
This might be true if the student enters the information correctly, and has the calculator set to the correct mode. And this is assuming that the student will only ever need values within the range of the inverse trigonometric functions.

In general, however, the tutor's suggestion (based on years of experience) is much more likely to lead to the student's future success -- not that the student is probably watching this thread that you resurrected, but I'd hate to see other students, reading this thread later, coming to the conclusion that they needn't learn how sine and cosine operate, "since" they need "simply" only punch buttons on their calculators. :shock:

Eliz.
 
masters said:
Pretty scary picture for someone who's having trouble with finding the angle when sin x = 1/2.

It would help if they knew that the ordered pairs are in the form (cos x, sin x).

If you have a calculator with inverse sin (sin[sup:1ron3jnr]-1[/sup:1ron3jnr]), then simply punch sin[sup:1ron3jnr]-1[/sup:1ron3jnr](1/2) and enter. The answer should be 30 deg, right where the unit circle says it is.
Click to expand...

Oh please...DO not tell students to "punch things into their calculator"!!!!!!!!

I'm really worried when students do NOT know the functions of the special angles! AREN'T you???

A student should KNOW (without a calculator) that sin 30 = 1/2, (and the functions for the rest of the basic special angles like 30 degrees, 45 degrees, and 60 degrees) as well as the quadrantal angles!

I guess I am coming to understand why it is that trig students are having so many difficulties these days.

Skeeter posted the diagram of a unit circle...GREAT STUFF. But....all a student really has to know is the first-quadrant values for each of the trig functions (well, really only sin, cos and tan), and the rules for the SIGNS of the functions in different quadrants.

Some of us were in college in the BC (before calculator) days...we learned the unit circle definitions...we did FINE. Why can't students learn this today? It makes them understand the genesis of the definitions...which is a GOOD thing, I think.
 
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