Trigonometry find the opposite side

In summary, the formula for finding the opposite side of a right triangle is O = A*tan(θ), where O is the opposite side, A is the adjacent side, and θ is the acute angle between the two sides. If you only have the angle and the opposite side, you can use the equation A = O/tan(θ) to find the adjacent side.
  • #1
Pin Head
23
0
Hi,
I'm a bit curious on how do I find the length of the Opposite side of a Right Triangle,
now I have look a Soh Cah Toa, Now say if I know the length of the Adjacent Line and the the angle of the right triangle which formula should I use?

I thought about Toa is this the way I solve for the opposite?

opposite = tan degree / adjacent
 
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  • #2
Do you understand what the mnemonic SOH-CAH-TOA means?

In response to your question, it's NOT true that "opposite = tan degree / adjacent". The correct formula is tan(##\theta##) = oppposite/adjacent, where ##\theta## is the acute angle you're looking at, opposite is the side opposite to ##\theta##, and adjacent is the side that is between ##\theta## and the right angle.
 
  • #3
Yes I understand Soh Cah Toa but I am using the equation to find the side of an unknown
side and the formula I'm using is
Example

tan = opposite / adjacent
but I only have the opposite side and the angle so to find the adjacent side I used this formula

24 / tan 42 degrees = 26.654700355900628883443567139963

adjacent side = 26.654700355900628883443567139963

But now the side I want to find is the Opposite side, do I used the same equation but put the angle tan degree in the Opposite side and divide by the adjacent side to find the Opposite side

tan degree / adjacent = Opposite side ?

opposite = ?
 
  • #4
Hi,
Sorry my mistake The formula I should of used is

adjacent * tan = opposite

example

12 * tan24 = 5.342744223702433967068404367748
 
  • #5
Pin Head said:
Yes I understand Soh Cah Toa but I am using the equation to find the side of an unknown
side and the formula I'm using is
Example

tan = opposite / adjacent
but I only have the opposite side and the angle so to find the adjacent side I used this formula

24 / tan 42 degrees = 26.654700355900628883443567139963

adjacent side = 26.654700355900628883443567139963

But now the side I want to find is the Opposite side, do I used the same equation but put the angle tan degree in the Opposite side and divide by the adjacent side to find the Opposite side

tan degree / adjacent = Opposite side ?

opposite = ?

It's pretty simple algebra. The basic formula is
tan(θ) = O/A ... (1)

If you know the angle, θ, and the adjacent side A, and you want to find the opposite side O, multiply both sides of the equation above by A.
This gives you O = A*tan(θ)

If you know the angle and the opposite side O, and you want the adjacent side, A, multiply both sides of equation 1 by A, and then divide both sides by tan(θ).

tan(θ) = O/A
A*tan(θ) = O
A = O/tan(θ)
 

1. What is the opposite side in trigonometry?

The opposite side in trigonometry refers to the side of a right triangle that is opposite to the angle being considered. It is also known as the side opposite to the hypotenuse.

2. How do you find the opposite side in trigonometry?

To find the opposite side in trigonometry, you can use the sine ratio, which is defined as the ratio of the opposite side to the hypotenuse. You can also use the Pythagorean theorem to find the length of the opposite side if the other two sides of the right triangle are known.

3. Can you find the opposite side without knowing the angle?

Yes, you can find the opposite side without knowing the angle by using the Pythagorean theorem. The Pythagorean theorem states that in a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the other two sides. Therefore, by rearranging the equation, you can find the length of the opposite side.

4. What is the opposite side if the angle is 90 degrees?

If the angle in a right triangle is 90 degrees, then the opposite side is equal to the side opposite to the right angle, which is also known as the base of the triangle.

5. Can the opposite side be longer than the hypotenuse?

No, the opposite side cannot be longer than the hypotenuse in a right triangle. By definition, the hypotenuse is the longest side of a right triangle, and the opposite side is always shorter than the hypotenuse.

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