# FAQ: When to use law of sines and law of cosines?

## When can law of sines be used?

The law of sines can be used to compute the remaining sides of a triangle when two angles and a side are known—a technique known as triangulation. It can also be used when two sides and one of the non-enclosed angles are known.

## How do you know when to use Sin Cos or tan?

Sin is equal to the side opposite the angle that you are conducting the functions on over the hypotenuse which is the longest side in the triangle. Cos is adjacent over hypotenuse. And tan is opposite over adjacent, which means tan is sin/cos.

## What is the main importance differences between using the law of sines and the law of cosines?

The cosine rule relates the cosine of an angle of a triangle to the sides of the triangle. With its help, the angles of a triangle can be determined, if all its sides are known. The sine rules gives the ratio of the sine of two angles of a triangle, which equals to the ratio of the corresponding opposite sides.

## What must you know to be able to use law of sines?

To use the Law of Sines you need to know either two angles and one side of the triangle (AAS or ASA) or two sides and an angle opposite one of them (SSA).

## What is the law of Triangle?

Triangle law of vector addition states that when two vectors are represented as two sides of the triangle with the order of magnitude and direction, then the third side of the triangle represents the magnitude and direction of the resultant vector.

You might be interested:  Readers ask: When was google docs created?

## 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. Remember that each fraction in the Sine Rule formula should contain a side and its opposite angle.

## How is sin calculated?

In a right triangle, the sine of an angle is the length of the opposite side divided by the length of the hypotenuse. In any right triangle, the sine of an angle x is the length of the opposite side (O) divided by the length of the hypotenuse (H).

## How do you find sin given Cos?

Triangles! Patterns of right triangles. All triangles have 3 angles that add to 180 degrees. Therefore, if one angle is 90 degrees we can figure out Sin Theta = Cos (90 – Theta) and Cos Theta = Sin (90 – Theta).

## Is tangent sin over COS?

Today we discuss the four other trigonometric functions: tangent, cotangent, secant, and cosecant. Each of these functions are derived in some way from sine and cosine. The tangent of x is defined to be its sine divided by its cosine: tan x = sin x cos x.

## Why does the law of cosines work?

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.

You might be interested:  How to clean a vape pen

## What is the law of cosines and sines?

The Law of Sines establishes a relationship between the angles and the side lengths of ΔABC: a/sin(A) = b/sin(B) = c/sin(C). This is a manifestation of the fact that cosine, unlike sine, changes its sign in the range 0° – 180° of valid angles of a triangle.

## How do you use the law of cosines?

When to Use

The Law of Cosines is useful for finding: the third side of a triangle when we know two sides and the angle between them (like the example above) the angles of a triangle when we know all three sides (as in the following example)

## Is SAS law of cosines?

SAS” is when we know two sides and the angle between them. use The Law of Cosines to calculate the unknown side, then use The Law of Sines to find the smaller of the other two angles, and then use the three angles add to 180° to find the last angle.

## What is the law of sines ambiguous case?

For those of you who need a reminder, the ambiguous case occurs when one uses the law of sines to determine missing measures of a triangle when given two sides and an angle opposite one of those angles (SSA). If angle A is acute, and a = h, one possible triangle exists.

## How do you tell if there are two triangles law of sines?

Once you find the value of your angle, subtract it from 180° to find the possible second angle. Add the new angle to the original angle. If their sum is less than 180°, you have two valid answers. If the sum is over 180°, then the second angle is not valid.