Help! I am bad at Maths!

donvito99

I'm stuck on this...

sin A= -1/2, find two values for the angle A, where 0(degerees) is less than or equal to A, which is less than or equal to 360(degrees).

Alll I have so far is...

A=sin(to the power of)-1*(-1/2).

Thanks in advance.

gra26

I suggest starting by looking at page 9 in your log tables.

henbane

First off, you need to get which angle gives sin(x)= 1/2. Then figure out which two quadrants result in a negative sine value.

Fremen

Ok, first off, you're not looking for sin to the power of minus one. The notation looks the same, but you're looking for sin *inverse*. The difference is extremely important and it's the kind of thing they'll look for in an exam.

Ok, now on to the question. I recommend you actually draw this rather than just reading it:

Draw two axes (x axis and y axis). Now draw a circle centered at the axes. We'll take out units so that the circle has radius 1.

Pick any angle, and starting at the point (1,0), i.e. the rightmost point of the circle, move anticlockwise around the circle by that angle. So if you picked 90 degrees, you'd be at the highest point of the circle.

Now, read off the coordiates of the point you're at. The first coordinate is the cosine and the second is the sine. This is the *definition* of sine and cosine. Forget that "opposite over hypotenuse" rubbish you were taught at junior cert.

So, you're looking for rotations which will land you at points on the circle with Y coordinates equal to -1/2. Find the point (0,-1/2) and draw lines up and down, parallel to the Y axis. Those are the points you're looking for. Now, see if you can work out the angles. Post back here with your attempt if you get stuck.

Oh, and no-one's bad at maths, they just haven't found a way to relate to it.

rorysllvn

thanks confusing haha

Kareir

Fremen wrote: »

Oh, and no-one's bad at maths, they just haven't found a way to relate to it.

That's actually a really good point. I mean, i'm not great at maths, but if i can find a reason for something to work that relates to something physical, i'm really good at it, e.g. Trig.

_kar.