# How to use law of sines

## Can you use law of sines for SSS?

Use the law of cosines when you are given SAS, or SSS, quantities. For example: If you were given the lengths of sides b and c, and the measure of angle A, this would be SAS. SSS is when we know the lengths of the three sides a, b, and c. Use the law of sines when you are given ASA, SSA, or AAS.

## In what instances can you use the law of sines?

The Law of Sines is utilized whenever you have either Angle-Side-Angle (ASA) or Angle-Angle-Side (AAS) congruency. In fact, we will also learn one more type of congruency that the Law of Sines can be used in our next lesson titled the Ambiguous Case.

## Does law of sines work for all triangles?

The Sine Rule can be used in any triangle (not just right-angled triangles) where a side and its opposite angle are known. You will only ever need two parts of the Sine Rule formula, not all three. You will need to know at least one pair of a side with its opposite angle to use the Sine Rule.

## What is the difference between the law of sines and the law of cosines?

The law of cosines (also called “cosine law”) tells you how to find one side of a triangle if you know the other two sides and the angle between them. The law of sines (i.e. the “sine law”) does not let you do that. … You could use it, for example if you know two sides and the angles opposite those two sides.

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## Is Asa law of sines?

“ASA” is when we know two angles and a side between the angles. then use The Law of Sines to find each of the other two sides.

## What is a AAS triangle?

Whereas the Angle-Angle-Side Postulate (AAS) tells us that if two angles and a non-included side of one triangle are congruent to two angles and the corresponding non-included side of another triangle, then the two triangles are congruent.

## Can you solve an AAA triangle?

“AAA” is when we know all three angles of a triangle, but no sides. AAA triangles are impossible to solve further since there is nothing to show us size … we know the shape but not how big it is.

## How do you solve the law of sines?

How to Use the Law of Sines with a Triangle

1. Using the law of sines and the proportion.
2. fill in the values that you know. Use the given values, not those that you’ve determined yourself. …
3. Use a calculator to determine the values of the sines (in this case, rounded to three decimal places).
4. Multiply each side by the denominator under b to solve for that length.

## What is the law of cosines used for?

The law of cosines allows us to find angle (or side length) measurements for triangles other than right triangles. The third side in the example given would ONLY = 15 if the angle between the two sides was 90 degrees. In the example in the video, the angle between the two sides is NOT 90 degrees; it’s 87.

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## Where is angle of depression?

The angle of depression is the angle between the horizontal line of sight and the line of sight down to an object. For example, if you were standing on top of a hill or a building, looking down at an object, you could measure the angle of depression.

## What are sines and cosines?

Sine and cosine — a.k.a., sin(θ) and cos(θ) — are functions revealing the shape of a right triangle. Looking out from a vertex with angle θ, sin(θ) is the ratio of the opposite side to the hypotenuse , while cos(θ) is the ratio of the adjacent side to the hypotenuse .

## How do you remember the cosine rule?

You only need to remember the +2abcos(C) bit. Yep. It’s rearranged to resemble Pythagoras’s formula.