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Equivalent expression of sin(arctan (x/3))

1 Answer

3 votes

Answer:


(x)/(√(x^2+9))

Explanation:

Let
u=\arctan((x)/(3)).

Then
\tan(u)=(x)/(3).

Construct a right triangle.

Make one of the non-right angles
u.

Recall
\tan(u) is equal to the ratio of the side that is opposite to
u to the side that is adjacent to
u.

This means opposite side
=x while adjacent side
=3 since
\tan(u)=(x)/(3)=\frac{\text{opposite}}{\text{adjacent}}.

We can find the hypotenuse by using the Pythagorean Theorem.


(x)^2+(3)^2=(\text{hyp})^2


x^2+9=(\text{hyp})^2

Take the square root of both sides:


√(x^2+9)=\text{hyp}.

Recall
\sin(u) is equal to the ratio of the side that is opposite to
u to the hypotenuse.


\sin(\arctan((x)/(3)))


\sin(u) -->Because we let the inside equal
u.


(x)/(√(x^2+9)) -->Because
\sin(u)=\frac{\text{opp}}{\text{hyp}}

User Usealbarazer
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