M1 Edexcel help Watch
E.g. with this sort of queston http://img.prntscr.com/img?url=http:...om/xdmN4K1.png
How do I know whether to do sine or cosine, and how do I work out the sine and cosine of an angle when given the tangent of that angle?
My teacher's attempted to explain it using the fact that sine is for slope and that if an angle is enclosed then cosine should be used.
Say I get tan (x) = 3/5, how does this give me sin (x) and cos (x)? I don't understand trigonometry too well.
As tan(x)=3/5=opp/adj. You can construct a RA triangle for reference with the opposite side to the angle being 3 and the side adjacent to the angle being 5.
From this, you should be able to work out the missing side's length using the formula and finding out the values for sin(x) and cos(x) using the identities I provided above.
R (\): R - 3g cos(30) + 36 sin(30).
And diagonally top right for part b, then using F= mew x r.
R(/): -F + 36 cos(30) - 3g sin(30)
Just a query, say I did it both ways in the exam as I wasn't sure, and they mark whichever way scored higher (I think), would I still get the marks? The only one I was really sure about with that example was the 36 cos/sin (30).