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Further Maths Trig Question

Angle Y is acute.
Capture.PNG
where p is a constant greater than 1.

Work out the expression for sin y in the form (attached picture)
Original post by Retsek
Angle Y is acute.
Capture.PNG
where p is a constant greater than 1.

Work out the expression for sin y in the form (attached picture)


Draw a right-angled triangle, mark one angle as yy, and the side opposite of it as p+1p+1 while the side adjacent to it as p1p-1 and move on from there to find sin(y)\sin(y)
Draw a triangle since we know the opposite = p + 1 and adjacent = p - 1

Do Pythagoras and work out the hypotenuse.

Then Sin(y) = opposite/hypotenuse
Reply 3
Original post by Retsek
Angle Y is acute.
Capture.PNG
where p is a constant greater than 1.

Work out the expression for sin y in the form (attached picture)


Sketch out a right angle triangle using the info of tan(y)
Then work out an expression for the hypotenuse.
Write down sin(y) (sin=O/H)
expand and simplify denominator


you should get sin(y) =p+1 / square root (2p+2)
Reply 4
Others got to it before me haha.
I don't think this is a further maths problem though. Maybe C3
Original post by OloMed
Others got to it before me haha.
I don't think this is a further maths problem though. Maybe C3


Further Maths GCSE.
Reply 6
Original post by OloMed
Sketch out a right angle triangle using the info of tan(y)
Then work out an expression for the hypotenuse.
Write down sin(y) (sin=O/H)
expand and simplify denominator


you should get sin(y) =p+1 / square root (2p+2)


Original post by Google22
Draw a triangle since we know the opposite = p + 1 and adjacent = p - 1

Do Pythagoras and work out the hypotenuse.

Then Sin(y) = opposite/hypotenuse


Original post by RDKGames
Draw a right-angled triangle, mark one angle as yy, and the side opposite of it as p+1p+1 while the side adjacent to it as p1p-1 and move on from there to find sin(y)\sin(y)


Thanks guys, it was a lot easier than I thought it was.
The part I was missing was the right angle triangle
Reply 7
Original post by Retsek
Thanks guys, it was a lot easier than I thought it was.
The part I was missing was the right angle triangle

Extension exercise if you feel like it:

Try the question again but this time angle Y is reflex instead of acute.
Reply 8
Original post by notnek
Extension exercise if you feel like it:

Try the question again but this time angle Y is reflex instead of acute.


I have no idea how you would do this...
Would you like get 360 minus Y?
Or would you use the trigonometric graph and find the corresponding value in the area between 90 and 180?
Original post by Retsek
I have no idea how you would do this...
Would you like get 360 minus Y?
Or would you use the trigonometric graph and find the corresponding value in the area between 90 and 180?


Is tan(y)\tan(y) positive or negative in 90<y<18090 < y < 180 ?

Try to use this fact.
(edited 7 years ago)
Reply 10
Original post by Retsek
I have no idea how you would do this...
Would you like get 360 minus Y?
Or would you use the trigonometric graph and find the corresponding value in the area between 90 and 180?

Ignoring signs (plus/minus), the right-angle triangle relationships between sin/cos/tan are true for any angle. And you can see this using the identities e.g. for sin/cos you have

cosθ=±1sin2θ\cos \theta = \pm \sqrt{1-\sin^2 \theta}

You need to think about whether the final answer should be positive / negative and then whether the fraction needs to have a sign added.
(edited 7 years ago)
Reply 11
Original post by notnek
Ignoring signs (plus/minus), the right-angle triangle relationships between sin/cos/tan are true for any angle. And you can see this using the identities e.g. for sin/cos you have

cosθ=±1sin2θ\cos \theta = \pm \sqrt{1-\sin^2 \theta}

You need to think about whether the final answer should be positive / negative and then whether the fraction needs to have a sign added.


Capture.PNG
And because between 90 and 180 sin X is positive, it must be a plus sign?
(Sorry late reply was having lunch)
Original post by Retsek
Capture.PNG
And because between 90 and 180 sin X is positive, it must be a plus sign?
(Sorry late reply was having lunch)


yes first quadrant all positive

Posted from TSR Mobile
Reply 13
Original post by Retsek
Capture.PNG
And because between 90 and 180 sin X is positive, it must be a plus sign?
(Sorry late reply was having lunch)

That's not right and I'm no sure how you got it.

What answer did you get for the original question?

Also I said the angle was reflex which is an angle greater than 180 :smile:
Original post by notnek

Also I said the angle was reflex which is an angle greater than 180 :smile:


Good god I legit read it as obtuse...

I think I'm more sleep deprived than I've realised today :lol:
Reply 15
Original post by notnek
That's not right and I'm no sure how you got it.

What answer did you get for the original question?

Also I said the angle was reflex which is an angle greater than 180 :smile:


Ahhh christ I don't even know anymore let me give it another go
Reply 16
Original post by notnek
That's not right and I'm no sure how you got it.

What answer did you get for the original question?

Also I said the angle was reflex which is an angle greater than 180 :smile:


Okay I've got
Capture.PNG
From using the trig identity involving sine and cosine
And because between 180 and 360 the sine graph is negative, it has to be 1 minus the fraction?

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