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 July 5th, 2017, 06:17 AM #11 Newbie   Joined: Jul 2017 From: Somewhere Posts: 13 Thanks: 0 but is it possible to cancel out like this? tan(34)=2tan(68 ) tan(1)=2tan(2)
July 5th, 2017, 06:54 AM   #12
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Quote:
 Originally Posted by Sigmarus but is it possible to cancel out like this? tan(34)=2tan(68 ) tan(1)=2tan(2)
No.

Do you have a calculator of some sort? Most scientific calculators have sin, cos and tan functions which you can use. In other words, you can check your answers! As studiot has said, they're just numbers (when an angle is specified).

Last edited by Joppy; July 5th, 2017 at 06:57 AM.

 July 5th, 2017, 07:00 AM #13 Newbie   Joined: Jul 2017 From: Somewhere Posts: 13 Thanks: 0 So the equation can be known as tan x 34=2xtanx68? might be a little off the question :/ Last edited by skipjack; July 6th, 2017 at 05:53 AM.
July 5th, 2017, 07:46 AM   #14
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No

I apologise that there was an error in the last line of my last attachment, so I have corrected it in this one.

It is important to realise that 'sin' on its own is meaningless.

You need to know the sine of what?
A sine is always a sine of something (some angle).

And sin(something) is always just a number.

So looking at what you are trying to write

tan × 34 is meaningless.

but tan(something) times 34 is

A number times 34.

If you want the tan of 68 then you must say the tan of (2×something)
or tan(2×34)

Note I realise that you are just encountering this stuff and are looking ahead at what you might do with it.
So I am trying to encourage your enthusiasm, by pointing it in the right direction.
Attached Images
 canceltrig2.jpg (76.6 KB, 6 views)

Last edited by skipjack; July 8th, 2017 at 08:05 PM.

July 5th, 2017, 03:01 PM   #15
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Quote:
 Originally Posted by Sigmarus So recently i have just learnt a bit about the basics of trigonometry and have some questions about it. Such as why is it when 2cos(θ)=√2 ,it will be cos -1(√2 /2) Thanks
Draw an isosceles right triangle with a hypotenuse of 1. Pythagoras and elementary
trigonometry tell us (for an appropriate choice of θ) that cos(θ) = cos(45) = √2/2. so
2cos(θ) = √2.

 July 5th, 2017, 03:05 PM #16 Newbie   Joined: Jul 2017 From: Somewhere Posts: 13 Thanks: 0 But what's the difference between tan(34) and tan x 34 :/ since tan is a function? So if atan(b)=asin(c) It can be tan(b)=sin(c) as a is not connected to the function? Thanks. Last edited by skipjack; July 6th, 2017 at 05:55 AM.
July 5th, 2017, 04:19 PM   #17
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Quote:
 Originally Posted by Sigmarus So if atan(b)=asin(c) It can be tan(b)=sin(c) as a is not connected to the function? Thanks
Yes! Maybe try doing this for a moment, just to familiarise yourself with what you've learned in algebra.

Let's call tan(b) = X and sin(c) = Y.

Now from your first equation we have,

a*X = a*Y. (The '*' symbol here means 'multipled by')

Now divide both sides of the equation by a,

(a/a)*X = (a/a)*Y. Of course, a/a = 1.

So now it's just X = Y. But we've already defined these two symbols, so we have,

tan(b) = sin(c).

 July 6th, 2017, 12:21 AM #18 Newbie   Joined: Jul 2017 From: Somewhere Posts: 13 Thanks: 0 But is tan x 34 = tan(34) ?
 July 6th, 2017, 01:07 AM #19 Senior Member   Joined: Feb 2016 From: Australia Posts: 1,231 Thanks: 425 Math Focus: Yet to find out. 34tan(x) = tan(34) tan(x) = (tan(34))/(34) x = $\tan^{-1}$ ((tan(34))/(34))
July 6th, 2017, 01:09 AM   #20
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Quote:
 Originally Posted by Sigmarus But is tan x 34 = tan(34) ?
What is "tan x 34"? Is the "x" a variable? Or a multiplication symbol?

Last edited by greg1313; July 6th, 2017 at 01:16 AM.

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