# What is the law of sines and when can it be used?

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## What is the law of sines and when can it 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.

## Where is sine law used in real-life?

One real-life application of the sine rule is the sine bar, which is used to measure the angle of tilt in engineering. Other common examples include measuring distances in navigation and the measurement of the distance between two stars in astronomy.

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

Practice set 1: Solving triangles using the law of sines This law is useful for finding a missing angle when given an angle and two sides, or for finding a missing side when given two angles and one side.

## What is sine rule used for?

The trigonometric ratios sine, cosine and tangent are used to calculate angles and sides in right angled triangles.

## How does sine rule work?

To solve a triangle is to find the lengths of each of its sides and all its angles. 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.

## Can sine law be used on a right triangle?

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.

## Is law of cosines only for right triangles?

Note that the length of the unknown side c is continually recalculated using the Law of Cosines. The Law of Cosines is a tool for solving triangles. From that, you can use the Law of Cosines to find the third side. It works on any triangle, not just right triangles.

## What is the difference between sine law and sine ratio?

1 Answer. The cosine rule relates the cosine of an angle of a triangle to the sides of the triangle. 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.

## When can you use the law of cosines?

The Law of Cosines is used to find the remaining parts of an oblique (non-right) triangle when either the lengths of two sides and the measure of the included angle is known (SAS) or the lengths of the three sides (SSS) are known.

## How do you solve for cos AB?

Finding cos(A + B) Each part must use the same denominator, the hypotenuse of the (A + B) triangle. The full base line, divided by the dividing line between angles A and E, is cos A (2). This dividing line, divided by the hypotenuse of (A + B) triangle, is cos B (3).

## What is the formula of sin a B sin AB?

sin(A+B)+sin(A-B). , [ Formula:- sinC+sinD= 2.

## How do you expand sin AB?

By using the formula of sin (A + B), sin (A – B) and cos (A – B) we can easily expand sin (A – B + C). Let us recall the formula of sin (α + β) = sin α cos β + cos α sin β, sin (α – β) = sin α cos β – cos α sin β and cos (α – β) = cos α cos β + sin α sin β.

## What is ABC sin?

We will learn how to find the expansion of sin (A + B + C). By using the formula of sin (α + β) and cos (α + β) we can easily expand sin (A + B + C). Therefore, the expansion of sin (A + B + C) = cos A cos B cos C (tan A + tan B + tan C – tan A tan B tan C). …

## What is sin 2A?

We will learn to express trigonometric function of sin 2A in terms of A. We know if A is a given angle then 2A is known as multiple angles. Therefore, sin 60° = 2 sin 30° cos 30°. The above formula is also known as double angle formulae for sin 2A.

## Is sin 2A equal to 2 sin A?

Hint: Question is based on trigonometric double angle formula for sin2A=2sinAcosA. As a first step bring all terms to LHS. Therefore, the value of A=0. Remember the basic trigonometry identities.

## What is sin 2A in terms of tan?

Trigonometric function of sin 2A in terms of tan A is also known as one of the double angle formula. We know if A is a number or angle then we have, sin 2A = 2 sin A cos A. ⇒ sin 2A = 2 sinAcosA ∙ cos2 A. ⇒ sin 2A = 2 tan A ∙ 1sec2A.

## What is the formula of sin 2 theta?

The double angles sin(2theta) and cos(2theta) can be rewritten as sin(theta+theta) and cos(theta+theta). Applying the cosine and sine addition formulas, we find that sin(2theta)=2sin(theta)cos(theta). Also, cos(2theta)=cos2(theta) – sin2(theta), see other forms for the two derivations.