# What is the law of sines

## What is the law of sines equation?

Simply, it states that the ratio of the length of a side of a triangle to the sine of the angle opposite that side is the same for all sides and angles in a given triangle. In ΔABC is an oblique triangle with sides a,b and c , then asinA=bsinB=csinC .

## When can you use law of sines?

When to 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.

## What is law of sines and cosines?

The Laws of Cosines and Sines. We saw in the section on oblique triangles that the law of cosines and the law of sines were useful in solving for parts of a triangle if certain other parts are known. … As usual, we’ll use a standard notation for the angles and sides of a triangle.

## 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.

## Why Sine is called sine?

The word “sine” (Latin “sinus”) comes from a Latin mistranslation by Robert of Chester of the Arabic jiba, which is a transliteration of the Sanskrit word for half the chord, jya-ardha.

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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.

## Does law of sines work with right triangles?

Note that the ratio of a side to the sine of its opposite angle is the same for all three sides. The Law of Sines says that in any given triangle, the ratio of any side length to the sine of its opposite angle is the same for all three sides of the triangle. This is true for any triangle, not just right triangles.

## How do you know when to use law of sines or cosines?

The sine rule is used when we are given either a) two angles and one side, or b) two sides and a non-included angle. The cosine rule is used when we are given either a) three sides or b) two sides and the included angle.

## 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.

## Does law of cosines work for all triangles?

It works on any triangle, not just right triangles. where a and b are the two given sides, C is their included angle, and c is the unknown third side. See figure above.

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## Why does the law of sines not always work?

Cases when you can not use the Law of Sines

Since we do not know an opposite side and angle, we cannot employ the formula. Or, just look at it: Remember when you have 2 sides, the angle must be non-included. By the way, we could use the law of cosines to find the length of the side opposite the 115° angle.

## 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.

## How do you solve SSS law of cosines?

To solve an SSS triangle:

1. use The Law of Cosines first to calculate one of the angles.
2. then use The Law of Cosines again to find another angle.
3. and finally use angles of a triangle add to 180° to find the last angle.