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trigonometry: (A2) Compound angles question

Hi,

Could someone help me out with what this questions asking me exactly?
DD602785-6377-4E9D-B5DC-96A4D68D2653.jpeg

Thanks :smile:
Original post by dxnixl
Hi,

Could someone help me out with what this questions asking me exactly?

Thanks :smile:

It is asking you to find the value of α\alpha such that 1+tanx1tanxtan(x+α)\dfrac{1+\tan x}{1-\tan x} \equiv \tan(x+\alpha)
Reply 2
Original post by RDKGames
It is asking you to find the value of α\alpha such that 1+tanx1tanxtan(x+α)\dfrac{1+\tan x}{1-\tan x} \equiv \tan(x+\alpha)

oH! thankyou :smile:

so i’m assuming x and α \alpha are two different variables?

sorry if i’m a bit slow we just went over this today ergh
Original post by dxnixl
oH! thankyou :smile:

so i’m assuming x and α \alpha are two different variables?

sorry if i’m a bit slow we just went over this today ergh


x is the variable.

Alpha is a constant value.
Reply 4
Original post by RDKGames
x is the variable.

Alpha is a constant value.

so is the answer 45 because x and alpha must be the same so that alphas eliminated on the RHS?

or am i just lost :’)
Original post by dxnixl
so is the answer 45 because x and alpha must be the same so that alphas eliminated on the RHS?

or am i just lost :’)

If "x and alpha must be the same", then surely x = alpha? I don't think that's what you actually meant to say...
Original post by dxnixl
Hi,

Could someone help me out with what this questions asking me exactly?
DD602785-6377-4E9D-B5DC-96A4D68D2653.jpeg

Thanks :smile:


Starting with: tan(x + a) = (tan a + tan x) / (1 - tan a tan x)
Notice that if tan a = 1, then the expression becomes identical to what is in the question: (1 + tan x) / (1 - tan x)
So let a = arctan(1) = pi/4 to get tan(x + pi/4).

Edit: or tan(x + 45) if working in degrees instead of radians.

Hope this helps :smile:
(edited 3 years ago)
Reply 7
Original post by Nick_2440
Starting with: tan(x + a) = (tan a + tan x) / (1 - tan a tan x)
Notice that if tan a = 1, then the expression becomes identical to what is in the question: (1 + tan x) / (1 - tan x)
So let a = arctan(1) = pi/4 to get tan(x + pi/4).

Hope this helps :smile:

OH RIGHT yeah i got it now ergh thanks 🤦*♂️
because tan(alpha) has to equal 1 to get the 1 in the numerator and so alpha can only be 45 degrees
thanks :smile:

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