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C3 Trig

trig.PNG

I came to get tan^2 0 = 49/576. So to get tan^0 as the question is asking, I square root it and end up with + or - 7/24. My question is how do I know which one is the right one? The answer in the textbook is tan 0 = - 7/24.Theta is meant to be reflex (180-360) but how do I apply this?
Reply 1
Original post by scientific222
trig.PNG

I came to get tan^2 0 = 49/576. So to get tan^0 as the question is asking, I square root it and end up with + or - 7/24. My question is how do I know which one is the right one? The answer in the textbook is tan 0 = - 7/24.Theta is meant to be reflex (180-360) but how do I apply this?


I am not sure why you have tan2θ\tan ^2\theta but

You know that the angle is between 180 and 360

But you also know that cosθ>0\cos \theta >0 so this tells you if you are in 180-270 OR 270 -360
Original post by TenOfThem
I am not sure why you have tan2θ\tan ^2\theta but

You know that the angle is between 180 and 360

But you also know that cosθ>0\cos \theta >0 so this tells you if you are in 180-270 OR 270 -360


I got tan^2 0 by turning cos 0 into sec 0 then sec^2 0 which is identical to (1 + tan^0) then I eventually had tan 0 on its own. It gives the right answer; but looking at the answer this was all stupid because they simply drew up a right angled triangle (with the known 24 and 25 values from cos theta) and simply worked out the tan value from there. But I understand now, cos 0 > 0 means it would have to be in the 4th quadrant and the solution for tan 0 would be negative. Thank you very much for your help
Reply 3
Original post by scientific222
I got tan^2 0 by turning cos 0 into sec 0 then sec^2 0 which is identical to (1 + tan^0) then I eventually had tan 0 on its own. It gives the right answer; but looking at the answer this was all stupid because they simply drew up a right angled triangle (with the known 24 and 25 values from cos theta) and simply worked out the tan value from there. But I understand now, cos 0 > 0 means it would have to be in the 4th quadrant and the solution for tan 0 would be negative. Thank you very much for your help


Ah I see, of course

I would have just drawn the triangle :smile:

But with trig there are often any approaches
Original post by scientific222
trig.PNG

I came to get tan^2 0 = 49/576. So to get tan^0 as the question is asking, I square root it and end up with + or - 7/24. My question is how do I know which one is the right one? The answer in the textbook is tan 0 = - 7/24.Theta is meant to be reflex (180-360) but how do I apply this?


Surely the easiest way is to find sinθ\sin\theta first and noting that it must be negative if the angle is reflex.
Would someone be able to help me with some C3 Trig?

I have 2 questions

a) √3 sin2(x) + 2sin^2(x) = 1

b) 4 tan2(x) tan(x) =1

Thank you.
Original post by adelmoulton
Would someone be able to help me with some C3 Trig?

I have 2 questions

a) √3 sin2(x) + 2sin^2(x) = 1

b) 4 tan2(x) tan(x) =1

Thank you.


(a) 2sin2x=1cos2x2\sin^2 x=1-\cos2x does this help?
(b) Use double angle identity to get an equation in tan(x)

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