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# C2 TRIG

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1. Question 20 in the mixed exercise of trig identities...

The diagram shows part of a curve with equation f(x) = 1+2sin(px+q) p and q being positive constants and q < 90.

Give than the coordinates of A and C are (0,2) and (45,0) respectively:

Calculate value of q - DONE

show that p = 4

Not sure how to do this one.. I get so far as...

sin(45p +30) = -30

But when I looked up the answer it should be

sin (45p+30) = 210

I now p is supposed to be postive - but just not sure where the 210 comes from because i get -30.....

This is the link to the question if you need the full thing...

2. Remember sin has two solutions (by this I mean the other solutions are just +/- 360 degrees). Say one is x. The other one is then 180-x. In your case 180--30=210 (degrees)
3. (Original post by christinajane)
Question 20 in the mixed exercise of trig identities...

This is the link to the question if you need the full thing...

Better fix it !!
4. (Original post by christinajane)
Question 20 in the mixed exercise of trig identities...

The diagram shows part of a curve with equation f(x) = 1+2sin(px+q) p and q being positive constants and q < 90.

Give than the coordinates of A and C are (0,2) and (45,0) respectively:

Calculate value of q - DONE

show that p = 4

Not sure how to do this one.. I get so far as...

sin(45p +30) = -30

But when I looked up the answer it should be

sin (45p+30) = 210

I now p is supposed to be postive - but just not sure where the 210 comes from because i get -30.....

This is the link to the question if you need the full thing...

If you draw the sin graph for -180<x<180, you can see that there are 4 different values x could take when y=-0.5 with the lowest, positive value being 210. Therefore that is the value you take and put in the equation
5. (Original post by NNB_Herath)
Better fix it !!
oops sorry!

https://0e90d90be05fe2865012661b731d...apter%2010.pdf
6. (Original post by Math12345)
Remember sin has two solutions (by this I mean the other solutions are just +/- 360 degrees). Say one is x. The other one is then 180-x. In your case 180--30=210 (degrees)
Ahhh ok that makes sense! thanks For that.

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