We will start off working on the right hand side.
<span>cot x - tan x </span>
<span>= [cos x / sin x] - [sin x / cos x] </span>
<span>= [(cos x)^ 2 - (sin x)^2] / [sin x cos x] </span>
<span>This is where it gets a bit tougher if you do not have your formula list with you. </span>
<span>(cos x)^ 2 - (sin x)^2 = cos(2x) </span>
<span>sin 2x = 2 sin x cos x </span>
<span>Note that by arranging the second formula, we will have sin x cos x = (1/2) sin 2x </span>
<span>Hence, we will get: </span>
<span>[(cos x)^ 2 - (sin x)^2] / [sin x cos x] </span>
<span>= [cos 2x] / (1/2)[sin 2x] </span>
<span>= 2[cos 2x] / [sin 2x] </span>
<span>= 2cot 2x </span>
(In English), your question would state the following:
<span>Calculate the circumference and circumference of the circle entered in a square 8 cm long.
</span>
So when finding the answer this this question, we know that the circumference would be the complete area of a circle.
So, I believe we would want to find what is the radius and the diameter that would make this circumference 8

.
The radius would then be (1.274).
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Now in your own language (Croatian).
<span>Dakle, kad pronađemo odgovor na ovo pitanje, znamo da bi opseg bio cjelokupno područje kruga.
Dakle, vjerujem da bismo željeli otkriti što je radijus i promjer koji bi ovaj opseg mogao učiniti 8cm.
Radijus bi onda bio (1.274).</span>
If period of

is one-half the period of

and
<span>

has a period of 2π, then

and

.
</span>
To find the period of sine function

we use the rule

.
<span /><span />
f is sine function where f (0)=0, then c=0; with period

, then

, because

.
To find a we consider the condition

, from where

.
If the amplitude of

is twice the amplitude of

, then

has a product factor twice smaller than

and while period of

<span> </span> is 2π and g(0)=0, we can write

.